Second Genesis

CHAPTER 7

The diskworld was a very strange place indeed.

Bram, weighing no more than an ounce or two, stood at the front of the landing ladder and looked out across the red twilight at a thin slice of landscape that stretched away into darkness.

Its edges were sharply defined against the starry night. Strictly speaking, there was no horizon at the end of it; the bleak, uniform vista dwindled to a vanishing point long before the eye could reach that hypothetical sykline some millions of miles beyond.

It gave Bram the illusion of standing on a very high, infinitely long ridge. Ahead was a flat, narrow plain of rubble that turned into a needle point piercing the black sky. On either side of him, not many miles away, was a sheer cliff that dropped down ninety million miles to a chasm filled with stars.

His weightlessness contributed to the dreamlike feeling of the place. The next person down the ladder jostled him unintentionally, and they both drifted a foot into the air before settling to the ground again.

Bram glanced into the other’s faceplate and saw by the blue glow of the helmet telltales that it was Jao. For once the red-bearded physicist was speechless. Both of them turned by common consent to look at the inner rim of their thin-sliced world.

The universe of stars gave way to a sky erased by stray luminescence, over what appeared to be a geometrically straight edge with no hint of curvature.

The brink of the world.

The great disks rose like goblin faces peering over the precipice, glowing a dull red of dying embers. As this queer world turned, they would rise in unison until they filled the sky. Even now, the big one ahead of them in orbit showed an angular diameter of fifty degrees, a hundred times wider than the sun would have been had it been visible.

From the present angle of view, almost forty million miles above the plane of the sun, one looked down on the inner disks. The three in the next orbit inward faced each other in a circle, like a conference of goblin children. Only one of these showed its glowing face; the other two were circular blots of darkness. Still farther inward hung more disks, getting smaller and smaller.

“I think I figured it out,” Jao said.

“Figured what out?”

“How to manufacture a diskworld.”

“How?”

Jao affected jauntiness, but his voice shook a little. “Oh, spin-up, foamed materials, superfilament, anchoring masses. I’ll tell you more when the geologist’s report is in.”

Bram looked across to where a squarish space-suited figure on its hands and knees was chipping away at rock with a little hammer. Each blow tended to lift him into the air, and then there would be a wait until he was sufficiently anchored to strike again; it must have been a maddeningly frustrating way to work. Enry had wasted no time. He had started collecting his samples only a few yards from the ship.

“What do you say, Enry?” Bram said.

His radio crackled. “Looks like ordinary rock so far,” Enry’s voice said. “Under a layer of dust.”

“Yar, from the spin-up,” Jao countered. “Plus seventy million years’ worth of micrometeorites. You’re going to have to dig a lot deeper before you get to what this planet’s made of.”

“Which is?”

“Mostly nothing. Wrapped around gases—oxygen, mostly, I’d guess. Combined with aluminum and probably carbon. You’ll have to get a chemist. But I’ll tell you this, Enry-peng-yu, when you get to it, it’s going to be a job taking the sample.”

Enry grunted and continued his chipping. He was gradually working out a low-gravity technique—striking his little outcropping from one side, then quickly reaching around to strike it from the other, and staying more or less in orbit around it.

“The rest of the answer’s there,” Jao went on, pointing at the moon overhead.

Bram raised his eyes to the zenith and instinctively wanted to duck his head. Everybody did. The ellipsoidal moon was so close—only a few diameters away—that it seemed in danger of falling.

You didn’t have to look up to be conscious of it. You could almost feel it hanging there with its pointed end aimed at your head. Feel it literally, perhaps. Its gravitational pull would not be insignificant compared with the diskworld’s feeble tug at the rim. Perhaps the fluids of the cells sent a message to the brain.

The pockmarked body measured scarcely a hundred fifty miles through the long axis. It might once have been an asteroid towed here by Original Man, Jun Davd had suggested, or a smaller moon of one of the dismantled gas giants.

There were artificial structures on the underside of the moon, visible even to the naked eye—a distinctly geometric jumble at the lower tip, with four enigmatic hairlines converging on it from the satellite’s waistline. The airless clarity brought it tantalizingly near.

“It makes you feel that you could almost jump up and touch it,” Bram said.

Jao chewed a hairy lip. “You know … I bet a space-suited man could reach the moon by jumping,” he said in a serious tone. “Assuming he could jump with an initial velocity of, oh, sixteen feet per second. Escape velocity ought to be somewhere around there. The surface gravity here’s about like a small asteroid. Like that comet head we visited.” His eyes almost clicked as he started doing calculations in his head. “Suit jets would help,” he conceded. “The trick would be landing safely on the moon, with only a pair of legs to come down on.”

“It might be quite a crash,” Bram said. “How far would he have to fall after capture—about a thousand miles?”

“Less than that.”

“We’ll visit the moon after we get organized here, I promise you. But I think we’ll do it in workpods.”

“There might be an alternative.”

“Huh?”

“We might be able to get there in climbers. We’ll know after we get to the ruins.”

The ruins—or their apparent focus—lay directly underneath the lower tip of the ellipsoidal moon. Lydis had wanted to land closer to them, but Jao had insisted that she land at least fifty miles away. “It might be dangerous,” he had said, but he had refused to say why. Bram had taken him seriously enough to order Lydis to comply. The distance would be inconvenient, but they had brought along a pair of walkers adapted to airlessness and low gravity.

“What are you talking about?” Bram asked.

“See anything over there? Use your top magnification.”

Obediently, Bram searched the distant ruins with his helmet telescope. The liquid crystal display emerged from its clear plastic sandwich and formed a circular image in front of his right eye. He squinted and adjusted the focus.

“I don’t see anything.”

“Turn up the contrast.”

“I think I see some kind of streak or scratch. It’s hard to be sure. I think it’s in my helmet … no, it stays put when I move. It may be a beam of light or a reflection. It’s pointing straight up in the direction of the moon.”

“That’s it,” Jao said.

“That’s what?”

“Oh, no. I’m not saying. I’m not sticking my neck out till we get there.”

“Watch out!” Bram’s suit radio said.

He stepped to one side and saw Lydis and Zef wrestling one of the walkers out of the hatch. They let go, and it floated down to the ground, where it unfolded, shook itself off, and inflated its passenger bubble. The biodevice was a tried and true version of the basic model the Nar had used for airless planetoids and nonrotating space structures. Its fragile, elongated frame would not have stood up under any semblance of real gravity, but it was strong enough for places like this. It had a submetabolism that worked on hydrogen and oxygen, and besides supplying energy, the auxilliary system had water and oxygen to spare for passengers.

“Well, let’s not waste time,” Jao said, with a hop and a dive toward the vehicle. “Did anybody pack a lunch?”

Enry was engrossed in his work. Now he was putting dust samples into little vials. Ame came bounding over from a fissure she had been studying. “That’s more like it,” she said. “Wait till I get my kit.”

Lydis drifted down the ladder and stationed herself in front of the spidery biovehicle. “Hold on,” she said. “We go out two at a time, at least till we know more about this place, and we keep the voice and homing circuits on at all times.”

“What d’ya mean?” Jao said. “The walker’ll carry three.”

“Sorry,” Lydis said. “That’s the way it’s going to be.”

Jao assumed an expression of great regret. “Sorry, Ame. You can take the next trip. Do you want me to bring back any rubble samples for you?”

Ame sputtered. “We’re going to have a first look at the ruins, and it needs someone with some archaeological and paleontological training.” She appealed to Lydis. “Isn’t that so?”

“I’d say so,” Lydis replied.

“Well,” Jao said. “Your daughter has spoken. I guess it’s Ame and me. Sorry, Bram. I’ll give you a running report over the radio.”

“Not a chance,” Lydis said firmly. “Neither your nor Ame is qualified on a walker. Bram’s the driver.”

It was Jao’s turn to sputter. “There’s nothing to steering one of those things.”

“There’s too much trouble an inexperienced driver can get into low gravity,” Lydis said. “You could turn over. Bounce it too high and come down the wrong way. Misjudge a ravine.”

“Sorry, Jao,” Bram said. “You can have the second ride. I’ll find out what that thing is. And give you a report over the radio.”

The walker loped across the jagged landscape, bouncing upward in great buoyant swoops that ate up the miles. Bram, with an occasional corrective jerk of the reins, kept a watchful eye through the inflated bubble on the route ahead. The tumbled lines of rubble they had to cross were not really dangerous to the walker, which was nimble enough to compensate for its stiff-legged gait when it came down wrong-footed on a boulder or crack. But of course it had no long-distance judgment.

“It’s shivery,” Ame said, glancing toward the great glowing hump of a disk that rose out of the ground to their left. As dull and rusty as the light was, it cast long gloomy striations of shadow across the stark plain.

“Shivery?” he teased her. “Is that some sort of technical term you paleontologists use?”

She nestled for comfort against him on the narrow bench. “It’s been dead and broken for millions of years. But I feel that it’s been waiting for us.”

“It has.”

“And that it’s watching us right now.”

“Nothing could live here.”

“We do. And this thing we’re riding in sort of lives.”

“You’re letting your imagination run away with you. But that’s not surprising. This place is haunted. By the entire human race.”

“Yes.” She shuddered. “It’s like our own graveyard. We’re supposed to be immortal. But so were they.”

“That’s why it’s important to find answers here, Ame. And that’s your job.”

She shook off the mood with an effort. “A job for more than me and Enry. We’re going to have to develop a real science of archaeology very quickly. We’ve never had the subject matter before. We don’t want to blunder about, destroying knowledge.”

“How do we go about it?”

“We’ll need a large labor force from the tree,” she said briskly. “We’ll have to establish a grid first, and a cataloging system. The librarians can help there, and everybody else will have to pitch in. Chemists, cultural scholars, everybody.” She challenged him with a direct gaze. “I can hardly wait to get a real team here and start the dig. How soon do you think that will be, Bram-tsu?”

“Right away, if everything looks all right. We’ll spend a few days here first—find a good place to set up a base camp, get an idea of the layout. Lydis ought to be able to move the ship a bit closer. That thing up ahead isn’t a danger now that we know where it is.”

The walker was at the top of a leap, and as it drifted slowly down, both passengers looked ahead through the bubble. The elusive streak at the center of the compound still could not be seen with the naked eye, even from a few miles away. But a couple of stops during the approach and a look through the helmet telescopes had confirmed that it was still there.

Bram had tried bouncing light off it from a hand laser, while Ame made photometer readings. Slashing back and forth with the beam, he had still obtained readings at what a rough triangulation told him was a height of over twenty miles.

Whatever it was, it was indubitably solid matter, and it reached straight up.

“Stop here,” Ame said. “I want to look at something.”

Bram reined the walker in. It reared up in the low gravity, then its front legs settled into the dust. Bram made it kneel, then followed Ame out through the lips of the bubble.

It made a primitive air lock, but it was the best that could be done within the limitations of the scrawny bio-machine. Very little atmosphere was lost if you managed the egress properly. You learned the technique quickly—arms stretched out with your head tucked between them, as if you were diving, then squirm the rest of yourself through sidewise, while the fat inflated edges sealed themselves around you, and a quick pop as you drew your foot through. He and Ame had stayed in their suits with their helmets on even though the bubble was fully pressurized with a breathable atmosphere of fifty percent oxygen. Lydis had insisted on that for safety’s sake.

Ame headed for one of the low ridges of rubble that crisscrossed the area, as she had done on previous stops. It looked no different from any of the other ridges of rubble as far as Bram could see.

“What is it?” he asked.

“Another rooftop,” she said. “Pretty intact under there, I should think. A warehouse or distribution center, maybe, from the size of it and from the way it’s situated—you can see how long that unbroken ridgeline goes on.”

“But why—”

“Come on. This way.” She had already planted a locater beacon in the debris for future reference, and now she scrambled up a low slope, sending up clouds of dust and chips that hung there in the inconsequential gravity.

“Careful of your suit,” Bram cried, but she had already disappeared over the edge. With a sigh he leaped after, soared over the peak with his legs tucked up, and dragged a toe to put himself down just on the other side. Unexpectedly, he found himself standing next to Ame on a forty-five-degree slope that ended at the base of what was ummistakably an uncovered wall of stone one hundred feet away.

“I thought I saw it when we were at the top of that last jump,” she said complacently. “Collapsed roof. Quake, maybe—we’ll have to ask Enry how quakes would work on a body with stresses like this one. Or maybe a meteorite strike. Look, it took four levels with it—it must be all tumbled down underneath there.”

She pointed, and Bram saw the broken ledges on the wall opposite, each with its cap of dust.

“And that will tell us how deep the regolith lies on a body like this one after we measure the slump,” she said. “You know, there must have been a lot of leftover junk in this system after Original Man got through with his construction project. We’ve got seventy million years’ worth of impact debris and dustfall. Lot of digging to do. Small bodies tend to lose mass because of high-energy impacts. The gravity doesn’t hold on to the stuff that fountains up. But on a body like this, even though the surface gravity is low because of rotation, there’s still the attraction of all that mass. The impact debris has no place to go, really, and over the eons it settles down in a slow rain and stays.”

“You’ve been studying your astronomy.”

She gave a pleased laugh. “It’s the same as geology in a place like this, isn’t it?”

“What do you expect to find under all that rubble?” He gestured at the tipped slope they stood on.

Her eyes shone. “Fossils, if we’re lucky. There’d be organic material if this was a food depot—or even if people lived or worked here, away from the operational center. People leave garbage. And garbage means mold, bacteria, microfossils. Maybe even the bones of vermin. Original Man must have had vermin.”

Bram remembered a childhood tale: The Dappled Piper of Shu-shih.

“Yes, indeed,” he said. “They called them rats.”

“Member of the order Rodentia” she said with a frown. “They’re in the mammal list, but Original Man doesn’t have much to say about them.”

“I’ll settle for a few dessicated bacteria. Would there be any DNA left after seventy million years?”

“Maybe. This place isn’t cold. But it’s airless and dry. Original Man ressurected something called Tyrannosaurus rex from a bone fragment after a similar period. In his twenty-first century. They kept them in zoos.”

He caught something of her excitement. “What a find a few bone fragments of Original Man would be! If we could do some DNA sequencing on a big enough sample, we could find out if he edited us before broadcasting our genetic code.”

“We don’t know his burial customs. But millions of people must have lived here over a period of time to operate the beacon. There would have been accidents … illnesses that got out of hand … the rare individual who was immune to the immortality virus—” She broke off, abruptly aware that Jao would be listening through the radio link.

“We’d better get going,” Bram said. “You’ve left a marker; we can send an excavation team later.”

But Ame was unclipping a folding shovel from her belt. She flexed the stub of a handle once to activate the memory plastic and an instant later had a proper shovel. “Let’s see how deep the regolith is where it’s slid down here,” she said. “Help me clear some of this away.”

Bram worked with his gloved hands while Ame shoveled, and within a tenth of an hour they had uncovered a smooth, hard gray surface.

“No miracle materials, those,” Ame said. “They made the walls and roof of ordinary melted and poured stone. They could afford to mold it thick enough to cover expanses like this. There was plenty of stone, and power to spare before they switched on the transmitter.”

“Twenty-three sextillion kilowatts, Jao figured,” Bram said. “Trillions of times as much energy as the entire Nar civilization had at its disposal. It’s a little disappointing to find that their building construction was so prosaic.”

“Sophisticated megaliths,” Ame said. “That’s what they are. Great slabs meant to outlast eternity. Only this one didn’t.”

She rapped the end of her shovel sharply; hydrogen atoms spilled from the reservoir they had fled to, preempted bonds again, and once more the shovel handle shrank to fit into her belt. She occupied herself for a moment chipping a rock sample from the slab. “I’ll take this back to Enry for analysis,” she said.

She bobbed to her feet a little too quickly, and Bram pulled her out of the air. “Ready?” he asked. He was anxious to return to the walker and continue toward the apparent center of the complex.

“Just a minute,” Ame said.

She looked down the rubble-strewn slope of where its edge abutted the vertical wall and studied the V-shaped trench it made. “There’s broken rock in places along the edge,” she said. “If any of them correspond to broken sections of the underside of the slab, we could get underground without digging.”

“No,” he said. “We’re not going to crawl through caves without any backup. It’s too dangerous. This place will still be here when we get back. Let’s get going. We’re wasting our air supply on the outskirts.”

“As long as we’re here, let’s just take a look,” she said.

“All right.”

He gave in and followed her down the slope. He didn’t like it. They were in a deep groove, cut off from sight of the walker and the never-ending landscape. Only the stars burned overhead.

Ame was unconcerned. She played the light of her torch along the join of the two surfaces. Color vision returned, showing Bram vitreous streaks of green, brown, and yellow mixed with the gray. Even to the naked eye it was apparent that the rubble had slid down the slope to cover any possible cracks to a depth of many feet. It would take a lot of work to clear it away.

But he was wrong. Ame’s torch played on a gaping black aperture that ran down the rocky crease in a spot that seemed remarkably free of rubble. In fact, the rubble seemed to be piled higher on either side of it.

“It goes all the way down,” she said. “About twenty feet to where the floor is. Big enough to squeeze through, and then there’s a sort of triangular tunnel made by the edge of the roof slab and the angle of the floor and wall. The tunnel’s clean—hardly any debris to clear away. I wouldn’t have expected that. The roof must have collapsed with miraculous precision. Half our work’s been done for us already. And when we explore the whole length of the cleft, we’re bound to find places where we can get through into the main part of the ruin.” Her voice rose with excitement. “Acres and acres of undisturbed …anything! Bram-tsu, why don’t we just—”

“No,” he said firmly. “We’re not going to go crawling in there now. For one thing, we’d be out of radio contact. Come on, Ame. We’ve seen everything there is to see for the moment.

“I suppose you’re right,” she sighed. She played the beam of her torch in widening spirals around the entrance. “But I don’t understand where all the rubble went.”

Then they saw the footprints.

The tracks converged on the hole from all directions. Heavy traffic. The reason they weren’t obvious in the immediate vicinity of the hole was that they became too thick there, obliterating outlines and churning up the dust. Besides, getting in and out of the hole meant belly crawling, further erasing any tracks.

But they were very plain farther away.

They were longer and narrower than an ordinary human footprint, but they covered about the same area and presumably would have supported a body of similar weight. The foot that had made the imprint had been encased in a tubelike boot with a ridged underside.

When he was able to catch his breath he said, “How long ago?”

Even his untrained eye could see that the outlines of the footprints were not as sharp as the prints he and Ame had left.

Ame produced a tiny measuring stick and compared the depth of the two sets of prints. Then she poked the rod into the dust in several places.

“They’re recent,” she said.

That startled him. “How recent?”

Her features worked within the helmet. “We’ll have to assume that the dustfall on this world has been diminishing during the last seventy million years, as the disks swept out their orbit. Dimishing on a logarithmic scale, maybe. Most of the dustfall must have taken place in the first few million years. But the roof must have collapsed, too, within a few million years of the time when Original Man abandoned the place, because of the later buildup that replaced the dust that slid down into the crevice.”

“Ame—how recent?”

“It could have been within the last thirty million years.”

Bram swayed in the low gravity. “More than forty million years after we thought the human race died out,” he whispered. He grasped her space-suited arm. “Could these prints have been made by a human foot?”

She shrugged. “Depends on what you want to consider human. It took the human foot only a few million years to evolve from a grasping organ that looked something like our hands. I suppose that in another forty million years, it could have evolved into something that looked like that.”

She splashed her light around the prints. “It’s hard to tell what might have been inside that boot,” she said finally. “But the elongated proportions aside, that could be a foot with the normal configuration of heel, instep, and toes. They always bend in the same place, so they had bones. Not like a Nar footprint that varied from step to step.”

“They brought animals with them.”

The light revealed meandering chains of shallow little paw prints, hardly larger than a human thumb. Then it struck Bram.

“What kind of animal could live in vacuum?”

The paw prints divided into five slender toes. Whatever had made them had been bare to space.

Ame leaned for a closer look. “A terrestrial animal. We’ve got quite a few drawings to go on. All terrestrial vertebrates had limbs based on a plan of five digits—even those that evolved into hoofs or wings. Bram-tsu, I’ve seen pictures of paws that must have looked something like these, on little climbing creatures like tree shrews, and raccoons, and … and squirrels!”

“And rats?” he suggested. “Yes, those, too.”

“Could this world once have had air?”

“N-no. Not with the low gravity. Besides, these prints show no signs of weathering. They’re perfectly preserved.”

Bram stood up. His knees felt weak. “We’ve never seen another terrestrial animal,” he said. “On all the Nar worlds, we were the only specimen. Now it appears that we’re standing on a world that once held at least two more specimens. Let’s get going, Ame. The sooner we finish our survey, the sooner you can start digging for fossils.”

“Bram-tsu, have you noticed something?” She moved her beam of yellow light around the area, holding it low to cast shadows.

The little paw marks were always superimposed over the footprints. Never the other way around.

“The animals were later,” he said.

“A lot later,” she said. She rested the light on a nearby cluster of paw prints. “Look at these. They’re very shallow because of the low gravity and because a creature that size wouldn’t have massed very much. They can’t be more than a millimeter deep. But even so, every detail is sharp. They’re not at all blurred by dustfall. They couldn’t possibly be more than a million years old.” She traced the paw prints with the light to where they disappeared into the crevice. “They might have been made yesterday.”

It was a ladder to the moon.

Bram and Ame left the walker at the edge of the massive circular housing and walked over to where the two thick ropes rose straight up into the sky, taut as bowstrings.

The ropes were semitranslucent and so thick around that it would have taken six or seven people joining hands in a circle to have embraced them. The bulge of the winding strands was sufficient to have served as a spiral staircase.

“The moon’s tethered,” Bram said. “Like a captive balloon.”

They stared up to where the cables disappeared into the sky. They were visible, Bram guessed, to a height of a couple of miles.

One of the cars that once had plied the tremendous mooring line was stalled about a hundred yards up, like a bead on a string. It was a flattish ovoid with portholes around the rim, and the beam of torch reached high enough to show it to be painted a jolly shade of red. The cable passed through the car’s center. Bram could only guess at the nature of the mechanism that climbed the braided cord—worm gears or ratchets or cogwheels. But there must have been an inner carousel that housed it, to keep the passengers from getting dizzy.

What a ride it must have been! Being whirled upward at thousands of miles an hour. How would they have managed turnover so that they could land on the moon right side up? Was there a way station at the point where the moon’s gravitational influence took over? A transfer point linking the two cables? There would have to be one car coming down for every car going up, to maintain equilibrium: One didn’t fool around with stresses like these!

His eyes moved across a mile of circular plaza to where a second set of sky ropes had been guyed. One of them had snapped. The end of the cable lay in ruins amid the buildings it had smashed. The dangling end of the rope was visible about a half mile up. The remains of an ovoid car that had slipped off the end of the rope lay strewn across the plaza.

Bram hoped no one had been in it. The disaster most likely had happened millions of years after the departure of man—maybe even millions of years after the time of the narrow-footed visitors. But the remaining set of cables had been strong enough to hold the moon down. The astonishing system had been engineered for redundancy.

Unable to resist, Bram reached out a cautious hand and touched the glasslike rope where it rose out of an encircling collar. He might have been touching a column carved out of solid steel. It was utterly hard, utterly immovable.

“Now we know what those hairline markings on the moon are,” he said. “The moon’s wearing a harness.”

“Bram-tsu, Jao is going crazy,” Ame reminded him delicately.

“Sorry, Jao,” Bram said, switching on the receiver of his suit radio. “I guess you’ve been listening to me and Ame oohing and ahing. I forget that you can’t see it.”

A howl of the purest agony reached him. After a moment, Bram realized that words were embedded in the incoherent gargling sounds.

“Describe it. What are the dimensions? What does the surface look like? What colors do you get when you flash light on it? How’s it anchored? Careful of loose threads, if there are any. You could lose a finger.”

Bram gave him a brief description of the rope and the surrounding installation. “I can’t imagine what it would be made of,” he said. “And I can’t see how it’s anchored. It just disappears into the ground.”

“Yar,” Jao said, breathing hard. “Each thread is a single continuous molecule that reaches from here to the moon. My guess is that it’ll turn out to be mostly oxygen bonded to silica, magnesium, and aluminum, with a carbon backbone to help out with all the connections. It’d be harder than diamond and with a higher tensile strength than amorphous boron to start with, and then there’d be some kind of submolecular weaving between adjacent chains … And, oh yah, you won’t find where it’s anchored, because it reaches all the way down to the original core of this world, forty-five million miles under your feet. That’s because it’s only a guide thread—part of the warp and woof that held this world together while they were spinning it.”

“Slow down,” Bram said. “I can believe in your tied, down moon because I can see the evidence here with my own eyes—and by the way, you’d better radio Jun Davd right away and tell him that we’ve solved the mystery of why the moons are lower than they ought to be for synchronous orbit. I’ll even accept your endless molecule till a better explanation comes along. But how could it support another forty-five million miles of its own weight?”

“It’s the other way around,” Jao said smugly. “The idea isn’t to hold the moon down. The moon is what holds the world up.”

Bram looked around at an apparently solid landscape. They were near one edge of the rim here. The avenues of rubble stretched to the opposite side, fifty miles away. The rectilinear mounds were higher at the lunar longitude than they had been on the outskirts of the enormous complex—the buildings had been taller and more important here. It had not occurred to Bram to wonder why the moonropes were peripheral and not centered, because, after all, the entire surface of the diskworld was the “equator.”

“You’re getting too farfetched,” he said, and waited for the next dizzying supposition from Jao.

“Am I?” Jao retorted. “I’ll bet you anything you care to name that when we cross that plain to the other side, we’ll find another cable car station and another set of ropes. Making an equilateral triangle with a fifty-mile base and its apex on the moon. Wait a minute! Make that a very narrow tetragon! Why not? The angle of divergence is minuscule on that scale. You might as well have parallel tethers. No, wait again! How about spreading the moon terminal still farther apart? At an angle that converges at the disk’s core? With a little truing of curves, you could have a ninety-million-mile section of parabola for your. antenna. Bram, we’ve got to map the whole topography of this disk! I’ll bet it has a concave cross section. Hard to detect, but it would make this razor’s edge of a rim the widest part, except for the leftover bulge at the hub!”

“I’d have thought that even a few inches of overhang at a height of forty-five million miles would add up to insupportable stresses.”

“Don’t you see?” Jao’s voice exploded in Bram’s ear. “This world was built like a suspension roof! It had to be! Otherwise, with the spin needed to keep it from collapsing under its own weight, the synchronous orbital points would have been embedded somewhere below the surface! There wouldn’t be a stable surface! All the people and the buildings and the topsoil would be thrown off into space!”

“What’s a suspension roof?”

“It was an idea one of the Resurgist architects had for building our sports arena in the human compound. Arthe, his name was. You strung cables from supporting piers and laid roofing material over them. You kept the internal air pressure of the building higher, to bear some of the weight. It was a way to provide a larger interior space unobstructed by load-bearing pillars. Nothing ever came of it. The council was too conservative and decided to stick with a Nar-style shell.”

“A whole world built that way?”

“Why not? It makes sense. And it fits the facts. We know this world is lighter than air. About twice the weight of helium on average. And when that average includes a rocky surface and two apparently rigid faces, then we’re dealing with an artifact that for all its size is mostly a gossamer nothingness enclosing more mostly nothingness.”

“Yes, I remember that Smeth proposed a honeycomb structure or a membrane enclosing a gas.”

Jao snorted impatiently. “But how do you build up a honeycomb out of a gas giant’s mass without it collapsing into a sphere after the first hundred thousand miles? Even if your honeycomb were as light as hydrogen? Especially when you’re starting out that much closer to the center of gravity—not like out here on the rim, forty-five million miles away from it, where we’re down to about six decimal places worth of zeros with a one hung on the end of them, and we’re staying attached to the surface mainly by courtesy of the local gravity of the crust. As for a membrane, one meteor puncture and you’d have the deflated skin of a world.”

“It would take more than one,” Bram demurred.

“This world’s had more than one,” Ame said tartly.

“All right, gang up on me,” Bram said. “Go on, Jao. Lydis, are you recording this for Jun Davd?”

“Yes,” Lydis said. “I can always add it to the reserve air supply. After cooling it down.”

“Who told you it’d be risky to make a cislunar landing approach?” Jao reminded her. “That didn’t turn out to be hot air, did it?”

“Let him finish,” Enry’s voice broke in. “It fits in with my seismograph readings. The waves damp out a few miles down.”

“Thank you, Enry. I’m glad there’s one member of our expedition with a little vision.” Jao continued smugly. “You start with an unremarkable rocky-type body—maybe the core of the gas giant they poured into their parts bin. Next you tow your twelve moons into place, positioning them so that they occupy the same synchronous orbit in a stable dodecagonal configuration. If you don’t have twelve leftover moons handy, you fill in with a few hefty asteroids.”

“Skip the details for now,” Bram suggested, “or we’ll never get there.”

Jao made a pained sound. “Then you drop a line from each of your synchronous moons and anchor them at the planet’s equator. While you’re lowering the lines, of course, you have to keep judiciously raising the moons’ orbits, to keep the center of gravity in the right place. Even with the lightweight filament you’re using, the mass adds up as the line grows.”

“So far you’re describing the construction of an ordinary orbital elevator,” Bram said.

“You recognized that?” Jao sounded pleased. “Not many people knew about that project.”

“I worked on a part of the problem at the biocenter,” Bram said. “Ordinary viral monofilament—the kind the Nar used for the bubble car cable network—tested well within the breaking strength limits, but there were still some problems with prolonged ultraviolet exposure that needed to be worked out.”

“What’s an orbital elevator?” Ame asked.

“You’re looking at one,” Bram said, pointing at the plaited crystal tower that rose into the sky with its impaled passenger vehicle still hanging from it like a spitted egg. “The Nar had a scheme for building a number of space docking stations on the same principle. Eventually they looked forward to a whole ring of them around the equator of the Father World, linked together for stability. It was well within the limits of theoretical possibility. But the Nar thought in terms of thousands of years, and there was no particular sense of urgency, oxygen and biologically produced alcohol for shuttle fuel being as cheap as they were.”

“The big difference here,” Jao rushed in, “is that Original Man’s skyhook used two tethers, anchored fifty miles apart. That was important. Even if they came together at the apex of an isoceles triangle twenty-odd thousand miles up, the slight lean from the true vertical wouldn’t have mattered that much. Not with the materials they had available.”

“Okay, you’ve got your twelve moons, bobbing up there like captive balloons, and connected to make a dodecagon—”

“To make a circle, Bram. The line bellies outward.”

“Okay, a circle. What next?”

“Next they started spinning the world. Faster and faster. At the same time, they began playing out more of their superfilament. They must have fed it out in a liquid form that instantly hardened—”

“There was a terrestrial animal called a spider that did that biologically,” Ame put in.

“Yah, I wouldn’t know about that. Anyway, they probably fed in the raw materials at the poles, from a couple of big gas clouds they had parked out in space. The oxygen and carbon could’ye come from carbon dioxide they siphoned off a hothouse-type planet—there’s one of those in almost every G-star system, same as gas giants. That must’ve been a sight to see—the two big vortices whirling from the poles millions of miles into space, while the tethered moons spun out farther and farther weaving a gossamer web between them.”

“You don’t think small, I’ll give you that.” Bram laughed.

“Now you start extruding your foam—mountains of it, oceans of it, following the network of filaments into orbit, the trapped bubbles of gases blowing the material up to two or three thousand times its volume before the molecules cross-link and become rigid. It maintains the disk shape, reaching a predetermined orbit at the limit of the spin force, with an excess material falling back to the surface. Foam that squeezes laterally through the web shears off, making a nice smooth face. Depending on the altitude, the excess stuff either slides outward or falls back to the hub. It’s exactly like the preliminary stages of the formation of a protostar … or … or a galaxy! The material settles more and more into a flat rotating disk! But now, with the growth of the disk, angular momentum is transferred and the spin slows down! So you get the stable situation we see here, with the moons traveling just a little faster—or lower—than they ought to be for synchronous orbit and maintaining the tension that helps hold the whole structure together.”

He stopped, out of breath.

“What’s happened to your rocky world at the center?” Bram asked.

“Oh, that? It’s smeared all over the faces of the disk. Some of it’s been flung out beyond the rim and fallen back, and we’re standing on it. And the rest of it’s a plug in the hole at the center of the disk, where the gravity is perpendicular to the disk surface. “It’s heavy there, that close to the center of gravity, I promise you!”

“What about it, Enry?” Bram said.

“It could be.” The geologist’s voice was muffled; he must have turned his head away from the helmet mike to check data. “I’ve got samples that could have come from the rocky core of a gas giant that broke up. Silicates that show signs of once having been under tremendous pressure. Millions of atmospheres worth—the kind of pressure that turns molecular hydrogen into metallic hydrogen. The paleomagnetism’s interesting. The orientation’s every which way. As if the samples originated elsewhere and were scattered all over the place.”

“What did I tell you?” Jao sounded smug.

“There’s something else,” Enry drawled.

“What?”

“The rocks show that there’s a steady leakage of gases from the interior of this … world. Oxygen, and carbon dioxide, and lighter gases like nitrogen and helium. The rim can’t hold on to an atmosphere, of course. But there could be a considerable amount of gas still trapped in the … cavities that Jao postulates.” There was a moment of silence with an unmistakable frown in it. “More than there ought to be, from the rate of leakage, after seventy million years.”

“The gases are subliming off the foamed surfaces,” Jao said quickly. “And maybe off the superfilament as well. Nitrogen, did you say? I’m going to have to rethink the chemistry of it. Plenty of oxygen, that’s for sure. Hey, we might be able to tap into it during our stay—take some of the load off Yggdrasil!”

“How far down would we have to drill to tap atmosphere?” Bram asked.

“I don’t know. It would take some pretty fancy mathematics to figure out the thickness of the crust, based on too many variables—the size of the original core, rate of spin-up, disk gravity gradients, surface friction affecting the dispersion of material … I think we’ll have to rely on Enry’s empirical methods. Theory falls in a case like this. It can’t be much, though.”

“Those bare paw prints,” Ame said. “Do you suppose…”

“Forget it, Ame. Any atmosphere belched out from the interior would instantly disperse. You’ll have to find another explanation.”

“There was life here within the last few million years—I’m certain of that,” she said stubbornly. “It’s…”

“What’s the matter, Ame?” Bram said.

She flashed her light around the base of the moonrope. “Look,” she said.

The tracks had been easy to miss in the permanent red twilight, especially when there was the awesome sight of that crystalline pillar drawing your eyes up instead of down. And the reflected light from directly above had tended to wash out the long, diffuse shadows cast by the horizon-filling sliver of the companion diskworld that rose above the brink.

But once you had noticed them, it was hard to see how the eye had skipped over them. Shallow as they were, they were perfectly plain, like inked thumbprints, a little smudged where the tiny paws had scrabbled in the dust. The myriad trails meandered a bit. But in the end pointed toward the soaring cable.

“They climbed it,” Ame said. “That’s where they went. They climbed to the moon.”

They had six hours to explore the central complex, Lydis told them. After that, they would begin to tax the walker’s ability to replenish their air supply. “I don’t want you to use your reserve bottles at all,” Lydis said. “That’s cutting it too close. I want you to come in with your reserve bottles intact. Understood?”

“Understood,” Bram told his daughter. He sighed. It had been five hundred years since she had been a little girl, but every once in a while it felt strange to be taking orders from her.

Ame was scrambling happily all over the mounds of rubble, leaving little electronic markers that would give off coded transponder signals when asked.

“Site number twenty,” she dictated to one of them. “Probable auditorium or lecture hall.” She followed with a series of dimensionless coordinates that would be fitted later into a triangulation grid by a computer.

“How can you tell it’s an auditorium?” Bram asked. “It’s just another dust pile, as far as I can see.”

“It’s fan-shaped,” she said, tossing him a grin over her shoulder. “We tend to think that public halls are supposed to be circular, with a stage in the center, because of the Nar influence. But this is a much more natural shape for human beings. And see, the focal point—abutting what might be classrooms or administrative offices—is at about the limit of distance from which a live lecturer or performer could be seen to any effect.”

Bram followed her around as best he could, climbing in and out of the walker, helping with the measurements, and operating the little portable thumper that located cavities beneath the surface.

“Libraries,” Ame exulted. “I’m sure of it. And museum warehouses and storehouses and depots and vaults for frozen samples. And all the support and recreational facilities you’d need for the population of millions that it would have taken to run this outpost—hydroponic farms, maybe even zoos! This will be a treasure trove for the archaeologists, Bram-tsu! And there’ll be middens—we’ll find seeds and organic refuse and bones…”

He didn’t like leaving her alone while he went off on his own side forays, and at one point he coaxed her into the walker for an excursion to the rim’s edge.

“Don’t go out any farther,” he warned. “I don’t know how secure this thing is.”

They were standing on the great skeleton arm of a gantry that extended out over the abyss—part of some sort of transport system that traveled an unknown distance down the face. Bram could see the stanchions that once might have supported an elevator or funicular dwindling with distance till they disappeared.

Hundreds—possibly thousands—of miles down the sheer face began a glittering fairy forest of tiny filaments that swept in a great arc until they could no longer be distinguished against the knife edge that cut the black night ninety million miles below.

“The feed array for the antenna system,” Bram said. “There must be others, equally spaced around the disk, aimed at a reflector at the hub.”

By this time they had worked themselves through to the opposite edge of the disk, facing the intergalactic night. The antenna complex was lit from above by ruddy moonlight.

The buried city, limned by mounded avenues of detritus, stretched all the way across the diskworld from rim to rim. And Jao had been right: There was another set of cables climbing to the moon on this side, too.

“So this,” Ame said, “was the voice of the human race?”

“Yes.” Bram dug through the centuries for an old memory. “My teacher, Voth, once said that humankind had learned to tame a sun’s power to shout across the gulf between the galaxies, but he couldn’t imagine how.”

He mused at the phased array, wondering at the scale that would allow its nearer ranks to be seen at such a distance. The elements must be miles high to be even remotely distinguishable—cantilevered or guyed against the topsy-turvy gravity. But that would have presented no problem to a race with moonrope at its disposal. And the gravity would be mild for the next few million miles, anyway. It would be a different story at the hub, where gravity would be crushing. Perhaps there were phase shifters installed at a safe radius. He would send an expedition down the face to see—in a space vehicle. And the physics would have to be carefully worked out so that the explorers would not find themselves slammed against a wall that had become a floor.

Bram shuddered at the thought of the mighty energies that once had been dispensed by that distant forest. In operation, it would have been a microwave inferno that would have sizzled a man to a crisp in milliseconds. No wonder a healthy stretch of no-man’s-land had been left—and not just to get past the gravitational edge effects.

Bram inched farther out on the gantry for a better look. Jao was going to insist on a full description. Too energetic a toe push sent him doing a handstand, and he walked a few steps on his hands before his boots settled down, holding on for dear life and being careful not to let go with one hand before he had a firm grip with the other. The asterioid-strength gravity was deceptive, he knew. He still had all his mass, and it was a long way to fall. Already, though he was no more than fifty yards over the edge, he knew that the horizontal component of the diskworld’s complex gravity was tugging every atom of his body toward itself in a complicated vector. He would have had to crawl out another million miles or so to feel anything, of course, but it was there nevertheless. But if he were to fall past reach of a handhold, he would be accelerated inexorably—at the dreamlike rate of about one thirty-millionth of a foot per second to start—until, at an unknown fraction of the distance to the center, the reaching forces of the disk would slam him into the tilted wall-scape at a velocity sufficient to abrade him into a long, wet smear.

It didn’t help a whit to realize that he’d have been long dead of suffocation, thirst, or boredom before that happened.

Bram stopped his balloonlike four-limbed outward prowl and wrapped himself securely around a thick strut with an arm and a leg while he surveyed the cliff face from his improved vantage point.

There was movement beside him, and then Ame was pressed up next to him, peering past his shoulder into the abyss.

“I thought I told you to stay put,” Bram said.

“Don’t be silly, Bram-tsu. I’m perfectly able to take care of myself. What could possibly happen?” She leaned out alarmingly. “Do you think we have enough time to climb down there for a look at some of those caves?”

“No!” he said, hearing himself sputter. In a more reasonable tone of voice, he said, “We’ll come back later with ropes and proper climbing equipment and a team of trained outside workers. Maybe we’ll round up a few tame climbers from Yggdrasil’s vascular system and ride them. And the climbers will wear safety lines, too!”

“It was just an idea,” she said mildly.

She unclipped her torch from her belt and played it over the vertical surface below. Seen up close, Jao’s “smooth face” was pocked with great pits and hollows. Looking at this cross section of a world, Bram could see where the crust began, a few miles below, like frosting on a slice of cake. The artificial material beneath was thinly covered with dust, and all sorts of domes, bulges, and the craters of burst bubbles poked above the rubbish of the sundered planet that had been used as a starter.

Closer at hand, vacuum welding over the eons had cemented a rocky cliffside in place. But here, too, even the languorous stresses that the diskworld was heir to had from time to time torn great chunks of material loose and left a pattern of cracks and cavities.

Ame’s beam found one of the holes. “I wonder bow deep—” she began, and stopped.

A pair of animal eyes shone in the beam of light for a startled second, then whisked out of sight.

“Oh!” Ame squeaked. She dropped the torch. It seemed to hang in space beside her; the light beam revolving in lazy circles. Ame recovered before the torch had drifted down more than an inch or two, caught it by the wrong end, and got it pointed at the cave again.

“Did you see it, too?” she whispered.

“Yes,” Bram said.

There was life in this place. And it was shy.

They stayed clinging to their dizzy perch until Lydis’s radioed warnings about their reserve air supply became too impatient to ignore. But the beady, luminous eyes never reappeared.

“It’s hunkered at the back of the cave, waiting for us to go away,” Ame said.

“Or there’s a way out through the rear,” Bram suggested. “There may be a whole system of burrows.”

She had tried the light in every opening it would reach. Far below, at the limit of the beam, they thought they saw a pair of pinpoints of reflected light for the briefest flash, but it was impossible to be sure. Finally, when Lydis began making threats, they gave up and hauled themselves back along the gigantic crane arm to the security of the rim.

They had left the walker parked a short distance away in a square at the intersection of two avenues of raised gravel. As they approached it, there was an explosion of movement around it, and dozens of small furry forms streaked away into hiding.

Bram gave a start. The little beasts were gone in an instant, before he had time to react.

“We scared them off,” he said.

“They must have been watching us the whole time, everywhere we went,” Ame said. “The ones here got up the courage to investigate the walker when we were gone so long.”

A wary little face peered out from around a block of stone, then jerked back as Ame’s light beam found it. Bram had a quick impression of huge round eyes, button nose, tiny mouth, and the flash of a bushy tail.

He found himself laughing. “They’re curious,” he said.

“They’re descended from terrestrial life,” Ame said. “That’s for certain. Like every picture I’ve ever seen. Everything in pairs—eyes, ears, limbs—just like us! And they’re furred—they’re not only vertebrates but mammals, too!”

“But how do they breathe vacuum?”

“I wonder … they’ve had millions of years to adapt to this place. Have you ever heard of whales?”

“I know the word. Stands for something big.”

“It was a real animal once. It adapted to a new environment, too. It learned to go for long stretches without breathing.”

They were at the walker now. The biovehicle was in the same kneeling position they had left it in. Bram gave Ame a boost, and she hoisted herself up to the passenger bubble. Then she froze.

“Bram-tsu! Look!”

He levitated to a position beside her, and she grabbed his arm. One of the little animals was trapped inside the bubble, scurrying about frantically, looking for a way out.

He stopped her as she as about to insert herself into the bubble. “Wait. Let’s see if we can shoo that thing out of there first.”

“Why? What harm could it do?”

“I don’t like the look of those little teeth.”

“It’s more afraid of us than we are of it. Oh, look at it, Bram-tsu! It’s so small! It’s just a little baby! It must have gotten separated from its mother. It’s terrified.”

Without waiting for a response, she swan-dived through the lips of the bubble. Bram followed, letting out at least a pound of air pressure in his haste.

“The poor thing,” Ame said, reaching for the small creature. It cowered against the far side of the transparent bubble, chittering at them. It was a little roly-poly thing, a ball of soft brown fluff with enormous golden eyes that were mostly round pupil.

“Ame, don’t touch it.”

“Nonsense! It couldn’t bite me through my vacuum suit even if it tried.”

She picked the creature up. It squirmed in her grasp, then seemed to give up. A moment later it was in the crook of her arm, clinging to her with four tiny grasping paws.

“It wants its mother,” Ame said. “Look, Bram-tsu, there’s a third eyelid for when it’s outside.”

He bent closer and saw the transparent nictitating membrane flick across the golden eye when the creature blinked at him.

“And little flaps for the ears, too,” he added, noticing the folds of pink flesh that creased reflexively to close off the entrance to the ear canal when he leaned too close, as if the little animal were trying to shut him out of its world.

“I think you’re scaring it,” Ame told him.

“No, it’s getting used to me.”

There were similar little flaps for the nostrils, but the creature’s nose twitched as it sniffed at him, and the flaps stayed open.

“I’ve seen pictures of fur, but I never dreamed it could be so soft,” Ame said dreamily. “Sort of like the twins’ hair, only all over. It makes you want to stroke it.”

“Ame, you keep those gloves on.”

“All right,” she said, patting the little beast with a gauntleted hand. It responded to the touch by snuggling up closer against her and wrapping its tail around her arm.

“We’ve got to start back,” Bram said. “We’ll come back and study them.”

“Jorv will be pleased,” Ame said. “All of a sudden, zoology isn’t a theoretical science anymore.”

“We’d better leave it here. We don’t have the facilities for keeping it alive during the trip back to the tree. It might not survive.”

“Bram-tsu, I love you. You’re a biologist, but it never even occurred to you to take it back as a specimen.”

“Well, I…” He flushed, “There’ll be plenty of time to study these animals at our leisure, find out what they eat, take tissue samples without hurting them.”

It was the Nar influence, he supposed—growing up among beings whose respect for any sort of conscious life was innate. Bram hoped the human race wouldn’t lose that trait with the passage of generations, but he had heard a few rather cold-blooded remarks from some of the younger tree dwellers.

“I hate to give it up,” Ame said. “It’s so cuddly and cute. You know, Bram-tsu, it’s all fluff. Underneath, it’s all scrawny.”

Reluctantly, she pried the small clinging creature from her body and eased it through the lips of the bubble. Bram saw the little fleshy flaps wink into place over ears and nostrils, and the creature’s fur seemed to puff up still further. Then it was floating to the ground with chubby grace, its tiny prehensile paws outstretched for contact.

It scampered off immediately. A larger beast darted from a cranny to intercept it, bowled it over, and nudged it with a button nose to a perch on her back.

“It’s found its mother, anyway,” Ame said with relief.

The mother beastie stood up on her haunches to bare her teeth at Ame and Bram, then scurried away with the baby fluffball clinging to her fur.

“I discovered them, and I’m going to name them,” Ame said. “I’m going to call them Cuddlies.”

CHAPTER 8

The airless streets were filled with space-suited tourists from the tree these days. They gawked at the massive excavated buildings, hunted for souvenirs in the rubble, and generally got in the archaeologists’ way. About a quarter of the population could be found on the surface of the diskworld at any given time, and the proportion was increasing as quickly as pressurized accommodations could be provided and atmosphere plants cloned.

Bram strolled down the broad, roughed-out avenue with Mim at his side, trying to keep his feet on the ground and rubbernecking like anybody else. A lot had been accomplished since his last visit; duties aboard the tree had kept him busy there for several Tendays. The tops of more buildings had emerged from the gray dust, and the tallest of them now stood at a height of twenty feet or more.

“It’s coming to life again,” Mim said, reading his thoughts. “You can almost imagine what it must have been like.”

“Hundreds of thousands of people going about their business—more than ever existed on the Father World, let alone gathered in one place,” Bram agreed. “We’ve found shops, theaters, even a sports arena where they played a game in midair with a ball and stick, and you were out of bounds when your feet touched the ground. And we’ve only begun to dig.”

Mim said wonderingly. “So many! As many as the Nar! And it looks crowded to me with only a few thousand here!”

“Most of the shirt-sleeve traffic between buildings would have been through the tunnel system. Still, it must have been pretty lively on the surface.”

Two space-suited people walked by, bearing a huge slab of granite that seemed to be covered with bas-reliefs. They were walking almost normally, thanks to the tons of mass that kept their boots pressed to the ground. One of them freed an arm to wave at Bram and Mim as they passed. The slab dipped, but the person caught it before it floated too far down out of its inertial path.

Bram waved back, frowning within his helmet. “I wonder where they got that,” he said. “They’re supposed to leave things in place till an archaeologist can have a look at the site. There are too many helpful amateurs wandering around.”

“Does it matter?”

“Very much, apparently. Ame says that the way finds are sited tells them as much as the finds themselves. And with bones especially, there’s a question of missing pieces.”

“Those long-footed skeletons?”

“She’s got some fairly complete ones. There’s a question about the dating. She sent word that there’s something she wants to discuss with me.”

“And lots of Cuddly bones?”

“Yes, and some they can’t identify. She thinks that they may have been pets of Original Man.”

Mim gave a subdued shudder and linked arms with Bram. “Ugh—bones! Still, it makes a good excuse for an excursion. The view gets more spectacular all the time.”

They both looked toward the horizon at the half-risen disk. It was a swollen red orb that stretched across most of the sky, its oblique angle squashing it out of shape. A smaller disk, back-to, made a black shadow across the glowing field. With the overhead moon brightening up, the diskworld was a reasonably well lit place these days—about on a par with the Father World nights when the lesser sun had been in the sky.

They had been in the system long enough for the diskworld’s rotation to bring this segment of the rim down almost to the plane of orbit. Yggdrasil, after some complicated maneuvering, was about a quarter diameter behind them again and catching up fast. At present, the trip from the tree took eleven days, the trip back even longer, but that didn’t stop the excursionists. With Yggdrasil renewed and the crust of the diskworld itself to tap, there was fuel literally to burn.

They continued their shuffling stroll. A Cuddly popped up out of a hole in the ground in front of them, sat up on its haunches, and gave them a fearless, big-eyed stare. The little animals had quickly allowed their natural curiosity to overtake their initial caution of human beings, and now they were all over the place.

Mim gave a cry of delight. “Aren’t they cute? Look at those clever little paws! They’re almost human! Can we take one back with us?”

“Why not? Half the people on the tree seem to have adopted a Cuddly. Or vice versa. They’re easy to tame, they eat anything, and they’re nice to have around.”

There had been some fear at first that the little burrowing beasts would spread uncontrolled through Yggdrasil’s vessels and passageways and perhaps interfere with the tree’s internal ecology. But that hadn’t been the case. The Cuddlies seemed to prefer human company, and they hung around the living quarters, attaching themselves to a particular person or family. They were affectionate little things, rubbing against a person’s leg until picked up and stroked, or even forcing matters by climbing up themselves to an arm or a shoulder. They were also shameless little beggars. Few people could resist them. They had quickly discovered all the outside exits, and during Yggdrasil’s “night” they liked to prowl about in naked space, among the leaves and branches. They could go an hour or more without breathing, living off the compressed oxygen in their accessory lungs or trapped in their amazing fur with its overlapping erectile follicles.

“Oh, look, I think it’s begging for food,” Mim exclaimed. “Do you have anything with you?”

“Afraid not. I had half a cornwich in one of my seal-pockets, left over from the shuttle snack bin, but I threw it away when we helmeted up.”

The big-eyed little furball, its coat fluffed out for vacuum, was balancing itself on one foot and its tail, holding out its right paw and right foot in tandem, like a pair of tiny human hands. It held the pose for a long moment, decided that Bram and Mim weren’t worth bothering with, and scooted off to find a better prospect.

“Oh!” Mim said, disappointed. “What are they, Bram? Were they brought here by Original Man?”

“Ame doesn’t think so. They’re too recent. She’s found the bones of what seems to be a transitional form they may have evolved from—and that only goes back about twenty million years. Before that, there’s a gap. All we know so far is that they have terrestrial DNA.”

The avenue they were walking along was one of the spokes of the great circular plaza that centered on the moon ladder—the initial dig had started here, and so far about a square mile of the surrounding city had been dug up. Now, as Bram and Mim emerged into the open spaces of the plaza, they both looked up.

A climber was coming down from the moon, an angular leggy shape that was silhouetted against the eerie red glow of the rising disk. As they watched, the artificial creature detoured around the stalled moon car, stepping carefully over the smooth surface and finding a foothold on the rope below. The climber was wearing a transparent ten-legged space suit that had been designed by, of all people, Marg; it included an extra tuck of material that fit over the passenger cup and billowed out to provide a habitable bubble for the five-hour climb.

“They’ve found Cuddlies on the moon, too,” Bram said. “Whole colonies of them. They’ve been established there for millions of years—and apparently they still travel back and forth. We’ve found fresh footprints around the rope. How they do it is a mystery. Even with a stop at the turnover station. Young Jorv thinks they have some way of taking extra air along, but that seems farfetched, clever little beasts though they are.” He gave a wide grin. “Of course, now they’re spoiled—they hitch rides with us in the climbers.”

“Are they digging up there, too?”

“Yes. We’ve found the remains of some tremendous engineering structures—extrusion devices on a scale that can hardly be imagined. Evidently, the original engineers played out the supporting filament from both ends when they were manufacturing this world.”

“So Ang told me. Jao can hardly contain himself now that his theory of suspension construction’s been vindicated.”

“We’re trying to verify it at this end, too. We’ve sunk several shafts at a slant and found that the moonrope extends as far down as we’re able to reach. We’ve gone past the crust now—it’s easy with digging machines in this low gravity—and penetrated through to the foamed understructure. We have to proceed carefully, though, to avoid disturbing the Cuddly burrows. They’re thick in the vicinity of the rope—it seems to be a main travel route downward. When the excavators started, they burst some of the bubbles and let the air out.”

“Oh, Bram, did they—”

“Relax. You can’t kill a Cuddly by taking away its air—they had plenty of time to squeeze through their little tunnels to the adjoining cavities. We messed up their gardens, though, No wonder the little rascals are such beggars.”

“Gardens?”

“Yes, we’ve uncovered a whole ecology down there. Jorv thinks that the ancestors of the Cuddlies carried seeds back from their surface foraging expeditions to the old granaries and warehouses of Original Man. Buried the seeds in their dens or excreted them—and some were still viable enough to sprout. Millions of years of evolution would have done the rest. And they would have carried bacteria, fungus spores—even algae—too. There’s insect life down there as well, marvelously adapted to the environment.”

“How can things grow in the dark?”

“There’s no visible light, true, except for bioluminescence. But the whole interior of the diskworld is suffused with infrared because of its energy-trapping structure, and the plant life’s learned to use it. For that matter, the Cuddlies themselves see quite well in the far red. Jorv suspects that the Cuddlies may even take a hand in cultivating some of the edible plants. That’s not unheard of in the animal kingdom. Something called an ant once did it—grew a fungus crop in its nest. Planted it, fertilized it, even chewed leaves to mulch it.”

“Could the Cuddlies be that smart?”

“It would be instinctual behavior. A survival characteristic developed through the ages. Mim, we’re finding out so much about terrestrial life from the books and microrecords in the libraries we’ve unearthed and from studying the organisms in the Cuddly burrows. Earth must have been a wonderful place! There were flying things that wove nests, rodents that built dams! Animal societies that cared for their young cooperatively! And we’re a part of that richness and diversity!”

She reached for his gloved hand and gave it a clumsy squeeze. “I know. Life will never be the same again.” She darted a a mischievous glance at him. “The food, for one thing. Marg’s been experimenting with some of those frozen seeds that were found in storage. She says we’ll soon be eating something called an artichoke.”

Bram laughed. “She’ll have us eating King James’s forbidden fruit next.”

“We already are,” Mim said quite seriously. “Wasn’t that the fruit of the tree of knowledge?”

Bram sobered. “More knowledge than we can absorb during our stay here. We’ll have to come back someday, Mim, after we find our world and get settled.” He took her by the arm. “Come on, we’d better find Ame and find out what she has to tell us.”

The archaeologists had chosen the big sports arena as their headquarters. It was the only place large enough to reassemble some of their finds. Most of it was still underground, a tall interior space that the diggers had gained access to after excavating only a couple of layers.

Bram and Mim followed the vehicle ramp downward to a domed receiving area where several of the monstrous Nar digging machines were parked awaiting service and a number of heavy-duty walkers were being carefully unloaded under supervision. A driver going off duty let them in through one of the small prefabricated personnel locks that had been ferried down from the tree and installed here.

The living quarters were a careless jumble of plastic cubicles around the perimeter of the dig. Bram and Mim gratefully accepted an offer of showers and fresh tunics before going on through to the huge cylindrical cavity proper; several hours in a space suit doesn’t do much to make a person presentable.

Banks of powerful lamps had been mounted far overhead as work lights. In their harsh glare, the cavernous interior took on a stark pattern of bright surfaces outlined by black shadow. Small groups of people in smocks or tabards were scattered across the immense broken floor, working at some of the hundreds of long tables where fragments of artifacts were being sorted and cataloged. More treasures were on display along the tiers of former spectator balconies in arrangements that made sense to the various specialists.

The larger reconstructions, some of them fairly complete, rose at intervals from the floor. Bram saw an articulated eight-wheeled surface vehicle taking shape—a series of portholed balls connected by flexible access tubes—and a towering plinth with the legs of a colossal metal statue still attached to it. Elsewhere, a section of wall with an engraved gate was being put together from a pile of stone blocks.

Bram pointed upward. “You can see where we patched the roof to pressurize the place—and we only had to do that because we broke through it ourselves. Otherwise, we only had to put in a few minor seals to make the place airtight again. They built well, these former humans. The supporting walls were fused stone and carbon, yards thick.”

“What kind of games did they play here?”

“We’ve found clues to that in some bas-reliefs we dug up. One game was played with a ball and paddles. You struck the ball with a paddle or kicked it with a foot while flapping the paddles to try to stay aloft as long as possible. There was a variation played only with a stick—the players dropped faster, and the plays were shorter. If you’ll look way up toward the ceiling past the lights, you’ll see the remnants of the drop grid. At the beginning of each play the teams were released simultaneously at a signal, in their starting positions.”

They continued threading their way between the tables across the wide floor. Progress was tricky because the floor was not smooth enough for a low-gravity scuff, and there was a tendency to bounce too high when surmounting some block of rubble—but they couldn’t sail over the obstacles, either, because they had to be careful of the tables.

“They drank out of strange cups,” Mim said, pausing at a table spread with shards of plastic ware.

Bram examined one of the more complete cups, a two-handled affair whose top tapered into a sort of spout that one could put into one’s mouth, almost like a nipple.

“Actually, that’s not such a bad design for a low-gravity environment. Prevents sloshing. Better than our own lidded cups,” Bram observed.

“That’s not what I meant. It’s the handles. They don’t seem to fit the hand very well. I’d find it very awkward to drink from one.”

Instead of being designed for one or two fingers and an opposing thumb, the handles were fat knobs with five vertical grooves. Bram could see what Mim meant. If one were going to hold a cup with two hands as if it were a bowl, the natural tendency would be to cradle it laterally, in the direction the wrists faced. If handles were needed at all, the grooves ought to have been horizontal—and there ought to have been only four of them, with a depression for the thumb on the opposite side.

“Maybe their wrists were more supple than ours,” he said. He smiled at a sudden comic image. “Or maybe they had no elbow room at their tables.”

“I’m serious.”

“So am I. About the wrist joints, anyway. Mim, what if Original Man didn’t become extinct seventy-odd million years ago, as we’ve always thought? What if he evolved past us—past the image of himself that he transmitted to the Virgo cluster?”

“Have you talked to Edard about the musical instruments?”

“What? No, Edard leads his own life these days. I haven’t seen him for a ten of Tendays.”

“They put him on one of the evaluation committees. Asked for his thoughts on fragments that seemed to belong to musical instruments. There’s a sort of pottery … flute, I’d guess you’d call it, in the shape of a tapered ovoid. It has finger grooves like the cups. And Edard says that the finger holes are placed in a peculiar way. It would make it almost impossible to play.”

“Well, perhaps Ame has an answer. Here we are. This is her bailiwick over here.”

He steered Mim toward one of the open bays on the perimeter of the floor, under the overhang of the first balcony. The bay was perhaps a quarter acre in extent. The bones didn’t take up as much room as the artifacts.

Ame came over to greet them. Her handful of assistants were working at tables with brushes and scrapers and buckets of plaster. One bushy-headed fellow was glued to a computer screen that showed animated images comparing the ways hip joints rotated.

“Bram-tsu-fu, Mim-tsu-mu!” she said, her face radiant with pleasure. “I’m so glad you could come!”

“How are the twins?” Mim asked, giving her a matriarchal kiss.

“Jabbering. And getting into things. Smeth’s watching them now. We have rooms at the guest house across the moon plaza. But I think I’m going to ask him to take them back to the tree. The low gravity isn’t good for their bones while they’re growing.” She laughed. “Besides, they’re enough trouble in two dimensions without having them flying through the air as well.”

Bram looked across at the row of skeletons wired upright to metal stands. “It looks as if you’ve put together some fairly complete specimens since I was here last.”

“Yes,” Ame said, looking pleased. “We were lucky enough to stumble across a burial ground. They seem to have interred their dead with much ceremony. That was a bonus. We’re learning quite a lot about their technology from the grave-objects. Don’t be deceived, though. The skeletons aren’t quite as complete as they look. We’ve filled in a few missing parts with plaster and resin by mirror-imaging, inference, trading bones, and so forth.”

Bram stopped the eager flow of words with a raised eyebrow. “Burial ground?” he repeated. “What did they die of?”

“Accidents, some of them. Degenerative diseases. Old age.”

“Old age!” Mim exclaimed. “But human beings are immortal!”

“Not always, Mim,” Bram reminded her. “The immortality virus was an addition to Original Man’s message. It came somewhere between the cycles of the transmission.” He turned expectantly to Ame. “The burial ground must have dated from the earlier epoch of the diskworld, then?”

“No,” Ame said. “That’s the problem. We haven’t dug down that far yet. Though the levels are mixed in ways they ought not to be—they’ve been disturbed.”

“How recent, then?”

“From everything we can surmise from the skeleton remains, the grave objects, the kitchen middens, and all the rest—the most recent habitation of this city was only about twenty-eight to thirty million years ago.”

“Original Man’s heyday was more than twice as long ago as that. Could you be mistaken?”

“Radiometric dating confirms that figure pretty much.”

“Original Man’s civilization fell,” Mim offered. “They lost their immortality. Forgot everything. Struggled up from barbarism. Then a new civilization emerged. Went star traveling again. Found humanity’s old beacon and began digging through the ruins—same as we’re doing.”

“That might fit,” Bram said. “The mixed levels. And some of the artifacts. They’re more primitive than the diskworld itself would suggest. That eight-wheeled jointed machine with the armored portholes and those crude metal-spring tires to absorb bounce in low gravity, for instance. Even we’re beyond that, with our Nar technology. Doesn’t it suggest a race with reborn self-confidence in the first flush of star travel?”

“Come over here,” Ame said. “I want to show you something.”

They followed her to the row of skeletons. A young assistant looked up from her work, smiled, and went back to wiring vertebrae together on a half-completed specimen.

“I’ve never seen a human skeleton, of course,” Ame said. “Just Doc Pol’s ultrasonic hologram of one. But you don’t have to be an expert to see that these skeletons aren’t right.”

She switched on the hologram, which appeared in a tinted plastic booth at the end of the row of skeletons, like one more skeleton frozen in a block of ice. Bram glanced at it for comparison, then turned his attention to the others.

The long-footed skeletons were approximately human size and shape and looked remarkably similar to Doc Pol’s study model if you discounted the long tail. But even without recourse to the hologram, Bram could spot the anomalies.

“They have the same general body plan as we do,” Ame said, “and the same major bones in the same places. But the arms are too short. The upper and lower leg bones are in the wrong proportion. The thumb opposes, but it’s the same length as the fingers. The cranial structures are wrong—the skull has about the same volume as ours, but it’s long rather than domed. And the dentition is very different.”

“And then there’s the tail,” Mim put in.

“Yes,” Ame said. “Evolution might have made many changes in man over a forty-million-year period, but surely it would not have given him back his tail.”

Bram chewed his lip. “It is possible, you know. There’s such a thing as back mutation or reversion. The mechanism isn’t well understood. But in this case you might envision it as the loss of a ‘switch-off’ gene that was an earlier mutation causing taillessness in some hominoid ancestor of man. The loss would leave the redundant tail genes that were still part of the DNA free to express themselves again.”

“You mean we could all grow tails again?” Mim said, wide-eyed. “I don’t think I’d like that!”

She cast a distinctly worried look at the short-armed, long-footed skeletons with their long whiplashes of added vertebrae.

Bram laughed. “It must have complicated their space-suit design, I’ll say that.”

“Oh, we’ve found an almost intact space suit,” Ame said. “The tail sheath was quite ingenious, with a whole series of little bleeder valves that allowed the tail to curl all the way around in a prehensile grip. Even in moderate gravity, they could have hung from their tails, leaving both hands free. We turned the suit over to one of the technology evaluation committees. You can see it on the upper balcony if you like.”

“Ame, how large a population of them was there?”

“It’s too early to answer that, but it must have been in the tens of thousands.”

“Too few to have filled this city, too many to have been just a scientific expedition. Ame, what were they doing here?”

“I can’t tell you that, either. We know that one of the things they were doing was exploring these ruins—just as we are. In fact, they’ve made our work a little easier. We’ve found at least one of their digs and its repository. They seem to have brought things up from a lower level one where the artifacts definitely were made for hands like ours—and they’ve arranged and cataloged their finds most conveniently.”

“Longfoot archaeologists.”

“Yes. They seem to have been just as interested in Original Man as we are. But the level of archaeological activity wasn’t high enough to explain their numbers. Otherwise, the whole place would have been dug up.”

“And yet they lived and died here.”

“For several generations, at least. We’ve found parts of children’s skeletons, too, and fetal bones along with the skeleton of one pregnant female. Bram-tsu, they gave birth to a dozen young at a time.”

“That doesn’t sound like human beings,” Mim said.

“No, not even after thirty million more years of evolution. But on the other hand, thirty million years before our line diverged from the hominids, our most probable direct ancestor was a small tree-dwelling animal called Aegyptopithecus. It was about the size of a Cuddly and looked something like a cat.” She halted. “Do you know what a cat was?”

“Yes. The little furry animals in the Goya painting.”

Ame nodded. “So you see, a lot can happen in thirty million years, even in the human line. Tail aside, the longfoots don’t seem that different from us.”

Bram said, “Ame, what were they?”

“We’re going to do some DNA studies and protein sequencing as soon as we can scrape together enough material. I’ll let you know.”

He got the answer to one of his questions a couple of Tendays later.

He was sitting in the cubbyhole he used as an office, going over Yggdrasil’s accounts—one of the more onerous chores he had to do as year-captain. Enyd had sent him an enormous stack of tally sheets—glucose balance; starch reserves; projected production of fats, oils, alcohol, and glycine over the next kiloday; currently available hydrogen and oxygen—and he was expected to okay the allocations today, if not yesterday.

The rasp of the intercom made him wince.

“I’ll get it!” Mim called. He heard her speak to someone, then she poked her head in and said, “That was Smeth from the trunk. The expedition’s just docked. Trist is on his way down now.”

“What’s his hurry? You’d think he’d want a little time to collapse first and get reacquainted with Nen. Or at least allow himself to be lionized for a few hours.”

Bram had been back on board Yggdrasil for only a few days himself; he’d left the disk city with the question of longfoot ancestry still unresolved. He’d had to plunge immediately into his accumulated paperwork and other duties, with no time to think about the matter further.

“Nen’s in surgery with Doc Pol,” Mim said. “Somebody managed to fall down a tracheid and smash an ankle. Trist prepared a preliminary report on the trip back. But he said he thought you’d want to know right away.”

“Know what?”

“That,” she said, “is what he’s on his way down to tell you.”

Trist arrived twenty minutes later; he must have been in free fall all the way. His yellow hair was disheveled, and he had a ripe space suit aroma—Lydis was still making her passengers suit up for drops and dockings—but he was full of unleashed energy, and his blue eyes, though rimmed with fatigue, sparkled.

He refused Mim’s offer of tea—a new custom instituted by Marg after she had read about it in some of the library material that had been brought up from the diskworld, subsequently experimenting with infusions brewed from Yggdrasil’s bark—and got right to the point.

“We did a thorough survey from space, of course,” he said. “Went as close to the hub as Lydis dared. Spotted over a hundred of the sites over a nine-hundred-billion-square-mile area. Some of the structures were still inflated after all this time; others were flat as corncakes. It was pretty obvious what they’d been up to. But we couldn’t be absolutely certain till we made a landing and deployed the climbers. We managed to visit four locations—brought back some goodies for the archaeologists, too.”

“And,” Bram said, knowing the answer, “what were they?”

“Camps,” Trist said promptly. “Work camps. They must have lived there deciyears at a time, repairing antenna elements, installing their own equipment to fill in the breaks.”

“They were trying to make the system operational again?”

“That’s the only conclusion that can be drawn.”

Bram leaned back and stared into space for a moment. “That would have been a tremendous undertaking, even with a work force of tens of thousands—or many times more than that, it may turn out. It would have meant committing themselves for generations.”

“They were willing to do that, apparently. Bram, can you imagine the conditions they must have endured in those inflatable camps? The ones closer to the horizontal gravity sectors were built out on scaffolding—with no place even to stand for kilodays, except for the tents and stringers. Dangling over eternity all that time while they worked. It wasn’t much better closer to the hub. Trying to adjust to the crazy angles, under heavy gravity with your weight tearing sideways at you. With the danger of falling with every step and an awareness of the penalties if you did. We didn’t set foot within ten million miles of some of the farther camps, and I can tell you, I still didn’t like it!”

Trist hadn’t heard about the tails. Bram told him.

“Whew!” Trist whistled. “That explains it. You’d need a tail to work in a place like that.”

“Ame thinks they may have been a species other than man. But the verdict isn’t in yet.”

“A new species to supersede man. I’m not sure I like that idea. It was one thing to deal with the idea that human beings were extinct. We’ve more or less accepted that from the beginning. But the idea of another species taking our place—that’s something else again. Gives us competition in this neck of the galaxy, Bram. The planet Earth may be overrun by these long-footed characters. Where do we go, then?”

“They may be our cousins.”

“Makes no difference. The fact that they were getting ready to patch up Original Man’s beacon tells us all we need to know. Different species or different order entirely, they were preparing to spread their own image through the universe. It bears out that old idea we used to talk about long ago, before the Nar sped us on our way to this galaxy—that there comes a time in the life of every intelligent species when it begins to dawn on them that the means is at hand for species immortality.”

“Yes, I remember.”

“Now we’ve got three cases. Original Man, broadcasting his genetic code to the Virgo cluster and beyond. The Nar, sending us to the heart of their own galaxy to do the same job for them. And now these people with tails. Except that they’re a little premature. They were able to take advantage of an installation that somebody else built. Bram, I just had another thought!”

“What is it?”

’You said that these tailed people weren’t immortal. Neither were the Nar. Neither was Original Man when he started broadcasting. What if this compulsion to spread around your genetic code is a stage that a species goes through before it attains personal immortality?”

“Hmmm. The night doesn’t seem so dark, then. The universe isn’t a bottomless hole. There’s time. Time to travel to the ends of the universe yourself someday. At least that’s what the little nagging voice inside you would be saying. Trist, you don’t suppose…”

“That Original Man never became extinct? That he simply gave up, packed up and went home after he’d been infected with eternal life long enough for the idea to sink in?”

“Yes. And then, somewhere along the way, acquired an immunity to immortality. Forgot things. Evolved into a new species. And then one day set out on a path to the stars again. And found the old beacon.”

“As I said before, it hardly matters. Whoever they were, they’re not us.”

“I’d like to send an expedition to one of the inner disks. And to the next disk ahead of us in orbit—see how close a duplicate it is to this one. We may have landed in the wrong place.”

“I’d give my spare shirt to go. But Bram, there isn’t time—”

“I’m going to call a tree meeting and call for a vote to stay here an extra year. We’re digging up treasure troves of material—whole libraries of it, and we’ve only scratched the surface. I want to get as much material transferred to Yggdrasil as we can. We can’t abandon a working party here, no matter how many eager volunteers there’d be. Not when the only habitable body in the known universe also happens to be our only starship. And there’s no telling when we’ll be back this way. It may be centuries before we grow another Yggdrasil and outfit it and can spare a population to crew it.”

“A year.” Trist furrowed his brow. “I’ll have to work out some orbits. The distances are huge, of course, but it’s not like ordinary interplanetary travel here … hmmm, we’ve got a body whose own orbital period is a year as our catapult, with no gravity to speak of to fight … add a modest boost…deboost to end up a hundred twenty degrees ahead … and for the return trip, a retro-orbit to lose orbital energy and rendezvous with your starting point in somewhat less than a year.” He gave Bram an engaging smile. “But I get Nen to go along with me as a medical officer.”

“Done,” Bram said.

Mim appeared with a tray. “Don’t worry, it isn’t tea,” she said. “Just old-fashioned cornbrew and some snacks.”

“Mim watch out!” Bram shouted.

A little ball of fluff streaked between her ankles and almost tripped her. She recovered her balance and managed to keep the tray level without spilling anything.

“Loki!” she scolded.

The Cuddly scampered up Trist’s leg, paused at his knee to be patted, then climbed to his shoulder and pulled at his yellow hair.

“Loki, get down and behave yourself,” Bram said. He apologized to Trist. “He gets into everything.”

“Oh, that’s all right, we have one of our own,” Trist said. He scratched the little creatures’s neck. “Where’d you get the name?”

“Loki? It was an old human god who was always getting into mischief. It seemed to fit.”

“Nen named ours Fluff. If she doesn’t stop overfeeding it, we’ll have to rename it Sphere.”

“It’s hard to resist one,” Mim said. “They’re the best thing we’re taking with us from the diskworld.”

Loki sat up and chittered at her as if he knew what she was saying. Trist broke off a corner of one of his cornsnacks and gave it to the little beast, which held the morsel in both paws and began nibbling at it.

“Yes,” Bram said. “I think they mean more to us than we realize. They’re the first terrestrial life form that humans have ever seen, after all.”

“Other than vegetables,” Trist said, popping a potato crisp into his mouth.

“Vegetables that we engineered ourselves or the Nar engineered for us. But Trist, just think of it, these little creatures carry an unbroken line of DNA that goes all the way back to the world that gave us birth.”

“DNA calls out to DNA, is that it?”

“Something like that. We know without having to think about it that these little animals are a precious link with an earthly heritage.”

Idly, Trist scratched the Cuddly behind one ear. It made a contented sound and snuggled against him. “There’s something wrong there,” he said lazily. “The first human being, as far as we’re concerned, was mixed up in a test tube by a Nar bioengineer. From native materials.”

“Ravel is Ravel,” Mim said. “No matter what instruments play it.”

“Hah! Good for you, Mim!” Trist conceded. “I’ll desist.” He took a sip of his drink. Loki tried to poke his muzzle into the cup, and Trist let him have a taste. The Cuddly sputtered and spat it out. Everybody laughed.

“Abstemious,” Bram said. “Maybe we can learn something from them.”

Trist fed the little pet another fragment of cornsnack to appease it. “It would be nice,” he said, “to go home to an Earth that was inhabited by Cuddlies instead of those tailed people with the long skinny feet.”

“Not likely,” Bram said. “Ame says the Cuddlies evolved on the diskworld from more primitive forms. That isn’t to say that some collateral branch with similar traits couldn’t have evolved on Earth in the meantime.” He frowned. “But we know what life form achieved dominance on Earth, don’t we?”

“They were rats,” Ame said.

She stepped back to let Bram have a better look at the exhibit that she and her section had prepared. Two of her colleagues—Jorv, the bouncy baby-faced zoologist whom Bram had met before, and a tall bony young woman named Shira, who was something called a “paleobiologist”—stood by with eager expressions on their faces.

Bram raised an eyebrow. “Rats? The pests of the ‘Dappled Piper’ legend?”

He scuffed cautiously closer. He hadn’t had time to readjust to diskworld gravity yet, and he was still stiff and tired from the ferry trip to the surface, though it was down to five days now.

“Rattus norvegicus to be exact,” Ame said. “The most successful member of the family and the one that would have been in the best position to succeed Original Man after man’s activities had changed the environment. They were highly adaptable, they were omnivores as humankind’s ancestors were, and in fact they resembled some of the primitive specimens on our own family tree.”

The computer-generated hologram showed three skeletons in the same scale. The center one was a life-size projection of Ame’s most complete longfoot skeleton—the one Bram had noticed when he first entered the work-bay. He recognized the skeleton on the right, too. It was Doc Pol’s familiar ultrasound figurine, the textbook example that Doc had learned his own trade from and that he now required his apprentices to memorize.

The third skeleton was something else entirely. Though the computer had made the bones stand in an upright position, the proportions were grotesque. The torso was absurdly long, with tiny little hands and feet and a head that was much too large for it. The bones would have been too spindly to support the creature in normal gravity. Bram saw immediately that the creature must have been a very small animal that the computer had brought up to the size of the other two skeletons for purposes of comparison.

Ame touched a button, and lines flashed from the center skeleton to the other two, showing correspondences. Though the longfoot skeleton and the human skeleton were superficially similar, it was immediately apparent that the disproportioned skeleton on the left had more in common with the longfoot specimen.

“You can see that what appears to be a backward-bending knee is actually what became a heel,” Ame said. “The creature would have walked on its toes. The shaft of the leg bone became a long, narrow foot. And of course, the tail is there, bone for bone.”

“Ame, this is marvelous,” Bram said. “I’m enormously impressed. How did you do all this?”

She looked pleased. “We had a breakthrough. Literally. One of the digging machines broke through to a layer where the stratigraphy had been disturbed. The longfoots had been busy there. They had a—a sort of museum of their own there. And a library. And biosample vaults. They had brought up and catalogued a whole biological cornucopia preserved by Original Man. It must have come as a wonderful revelation to the longfoots. They were interested in their own ancestry, you see. Original Man’s records predated their own fossil records.”

Jorv’s plump face beamed complacency. “Original Man did all the work for them,” he said, “and they did all the work for us.”

“We don’t have enough archaeologists to go around,” Ame said, “but all the amateurs are well trained by now. As soon as the digging machine operator saw what he was bringing up, he stopped, roped off the place, and notified the proper people.”

“As soon as they saw they were bringing up biological specimens, they got us,” Jorv bubbled. “You wouldn’t believe it! There were mounted skeletons. Arranged in classifications. And metal plaques to explain them. And supplementary materials—actual books preserved in nitrogen. And tapes and holochips. In Inglex and Chin-pin-yin. The longfoots probably couldn’t read them, but we could—right away!”

The attenuated paleobiologist, Shira, ran nervous fingers through stringy brown hair. “And there were actual tissue samples, too, still in a remarkable state of preservation. The rat-people—longfoots—had broken some of the seals, but others were intact. We were able to extract enough DNA and protein for sequential analysis.”

“There’ll be more,” Jorv interrupted. “We’ve only scratched the surface with this find. We’re trenching now, looking for the rest of it. And they thought zoology was a theoretical science! Bram-companion, when we get to our world, we’ll be able to recreate species! Stock our streams with trout, our forests with trees other than poplar! Did you know that Original Man had his own bio-vehicles—a sort of walker called a horse!”

“Well, that’s certainly a program for the future,” Bram said noncommittally.

Shira continued serenely, as if used to interruptions. “Until now, we’ve lacked the capacity to do molecular taxonomy in any meaningful way. Oh, we’ve been able to use cytochrome c sequencing to demonstrate that human beings are very far removed indeed from yeast—forty-five amino acid differences—not quite as far removed from cabbages, and closer still to heterochronic eggs. But now, of course, we have all those lovely tissue samples.”

“Horses,” Jorv said dreamily. “Zebras. Giraffes. Rhesus monkeys. Wolves. Original Man preserved them all.”

“And of course we’ve brought up scads of mouse bones from our deeper excavations. Man inadvertently carried mice and other vermin to the diskworld with him—just as, I suppose, he carried them with him everywhere he went. The mice didn’t manage to survive for long after humans departed the diskworld. They never adapted for airlessness, they weren’t able to burrow deep enough, and they quickly exhausted the more easily available sources of food. We found no mouse bones more recent than seventy million years old. But they still contained traces of cytochrome c.”

“And we had ourselves and Cuddlies available as a source of hemoglobin and serum albumin,” Jorv said. “Oh, there was no doubt at all!”

Shira brushed her hair back. “The longfoots were at several removes from us and Cuddlies—well beyond the limits of family or genus, let alone species. Farther still from Jorv’s giraffes, though we were able to do only DNA sequencing in that case. But the molecular differences between longfoots and mice—”

“Mus musculus,” Jorv interjected. “Same family as rats. If you remember your childhood Chin-pin-yin, it’s the same word. Big-mouse.”

Shira spared a tolerant glance for Jorv and finished what she had been saying. “…but the molecular differences between longfoots and mice were practically nil.”

Bram nodded at the longfoot skeleton. “That seems to settle it, then. Man did become extinct. And the next dominant species was that.”

Ame said, “We found something else.”

“What’s that?”

“We know how the Cuddlies got here.”

Bram picked his way down the tunnel, following Jorv’s bobbing yellow light. Loose gravel under his feet started slow-motion cascades as he proceeded, coming to rest long after he had passed. The lanky paleobiologist was right behind him, shedding enough light of her own for him to see by, and Ame brought up the rear. Bram, as an escorted guest, went unburdened; the other three wore many-pocketed tabards over their space suits and lugged an assortment of picks, hammers, and other small tools.

After what seemed like an endless trek, the tunnel opened out into a wide, low-ceiling space shored up by timbers. Other tunnels branched off the space, glimmers of light from a couple of them showing the presence of other work parties.

The thick timbers were ordinary vacuum-poplar. Seeing them brought a lump of homesickness to Bram’s throat till he remembered that vacuum-poplar had originated here, in the Milky Way, not in the Whirlpool galaxy.

Ame saw him looking. “The longfoots dug up a human lumberyard near here and took advantage of it. The wood must have been in vacuum and still good. Before that—” She indicated the branching tunnels where archaeological work was in progress. “—the longfoots used columns of native stone as well as steel griders that they brought with them. Evidently they didn’t have much of a structural plastics industry. It bears out your theory that they were a young civilization, newly come to star travel, Bram-tsu.”

“What was this place?”

“The longfoots had some of their own storehouses here. And living areas close by. We gleaned some insight into their social habits. There was some limited pair bonding in our sense, but mostly they lived in aggregates of fifty to a hundred members in which females were available to males on some kind of schedule of dominance. The living arrangements pointed to that, anyway. The females raised their young separately and cooperated in keeping males at bay for a period after parturition.”

“They don’t sound like a very pleasant people.”

“Rats don’t make very pleasant ancestors.”

Bram shuddered, remembering the fragment of film Ame had been able to show him. It had been part of an exhibit associated with the mounted rat skeleton and had shown a bedraggled brown animal with beady eyes and a naked tail greedily eating its way thorugh a store of corn, excreting as it went. Bram had been ashamed of his instant and automatic revulsion, telling himself that the rat was a life form like any other, with a right to existence. But Ame had told him that his reaction wasn’t unique—that rats seemed to raise the hackles of most humans.

“You’re being narrow-minded, Ame,” Jorv protested. “Seeing it from a human point of view. Different species, different biological imperatives. They might have been a perfectly decent folk. They acted cooperatively, after all.”

“Come here, I want to show you something,” Ame said.

She led Bram to a cache where specimens had been arranged with preliminary labels. There were bins of a dessicated, unfamiliar grain, shovel-size scoops, a broken ceramic jug.

But what caught Bram’s attention was a small animal skeleton on a slab of wood. The skull was crushed, pinned to the slab by a copper bar that was attached to a large spring. But enough could be seen of the jaw to show that it was still clenched around something that looked like a fossil nut, which was attached by a wire to a sort of pivoting tray.

“A trap,” Ame said. “The animal in it was a Cuddly.”

Shira tossed her lank hair back within the bowl of her helmet. “They poisoned them, too,” she said. “We’ve found piles of Cuddly bones around a feast of that same bait that one of them would have brought back to the burrow for the females and young ones.”

Bram was appalled. “But what a terrible thing to do.”

“No more terrible than what Original Man did to rats,” Jorv said.

“The longfoots carried their own vermin into space with them, just as man once carried rats and mice,” Ame said. “That’s what the vermin were. Cuddlies.”

“The Cuddlies’ ancestral form, actually,” Shira said. “They hadn’t evolved for airlessness yet. You can see that the rib cage isn’t enlarged for accessory lungs. And the toe of the rear foot is not fully opposable.”

“But I think that if we were to see one of these creatures in its fur,” Ame said, “we’d see it as a Cuddly.”

Bram studied the trap with distaste. “Ingenious and cruel,” he said. “The victim had to tug at the bait to pull it loose, and that released this strut that kept the spring armed. The animal’s head would be in position for the copper bar. Even if its reflexes were good and it drew back, it would still get its neck broken.”

“These little animals were pests,” Jorv said. “They got into the longfoots’ food supply. They were probably unsanitary. And they probably bit.”

“The longfoots tried diligently to exterminate them back on Earth. We found a sort of children’s picture book with a story about it. But the creatures must have been too clever, or too prolific, to be stamped out entirely. The longfoots must have been horrified to find that they’d transported them here.”

“Well, the Cuddlies outlasted the longfoots here, at any rate,” Bram said grimly. “Long after these … rat-people packed up and went back to Earth, The Cuddlies were able to survive on the diskworld long enough to adapt for vacuum. To adapt for space travel, when you stop to think about it—when you see the way they scamper around Yggdrasil’s branches and seem to enjoy it.”

“Their root stock must have adapted back on Earth, too,” said Shira.

“Yes,” Ame said “If the human race was never able to exterminate rats, and the rats developed into an intelligent species after man was gone, the same might be true for the proto-Cuddlies. They might be the longfoots’ successors back on earth by now. After all, they occupied a similar ecological niche.”

“What a delicious thought, Ame!” Shira exclaimed. “A world ruled by cousins of the Cuddlies! But would a six-foot intelligent Cuddly be as huggable?”

Ame laughed. “I can hardly wait to get to Sol and see. But Bram-tsu, we mustn’t leave till we finish our work here.”

“That won’t be for a while,” Bram said. “We had an all-tree meeting before I left. You’ve been voted an extra year.”

The long plain was dotted with depots of crated material, each with a little band of partisans gathered around it vying for priority. Processions of cargo walkers, roped together in long caravans led by space-suited drovers, plodded across the starlit diskscape toward the staging areas where the rocket-assisted pallets were being loaded. All the wheeled vehicles had been pressed into service, too, and they could be seen bumping lazily across the flat vista, some of them achieving temporary flight.

Bram, helping Jun Davd to cinch a saddlebag full of astronomical data in place on a kneeling walker, paused in his work to watch a shower of sparks lift above the horizon and rise toward the blob of silver light that was Yggdrasil, hovering just to the right of the pendant moon.

“That’s the third in an hour from the other side,” he said. “The museum’s launchpad, it looks like. They must be working overtime.”

“They’re overloading their pallets,” Jun Davd said. “I’m surprised some of ’em got off the ground. I was over there yesterday helping the dispatcher to figure weights and balances, and we had to make them take off a big statue of three naked men wrestling a snake. Would have spoiled the trim—had the platform tumbling end over end. Had one of those art fellows almost in tears.”

“I’m sure they got it off later.”

“They’ve had a year and a half to loot that museum. I thought the idea was to take a small representative sample and leave the rest for the ages—or for whenever we can get back this way.”

“You know how it is. All of a sudden we’re about to leave, and they start having second thoughts. There’s this last-minute rush. Everybody’s suddenly discovered that there are things they just can’t bear to leave behind—the historians, the archaeologists, the agronomists, everybody.” He laid a hand on the saddlebags. “You, too, it looks like.”

Jun Davd grunted. “It just occurred to me that it might be a good idea to abscond with part of the backlog of original plates—do you know, their astronomers were still recording images on light-sensitive paper for centuries after they had more advanced methods available? Oh, I’ve got all the electronically stored data I need, but it’ll take years—decades—to go through it all, and I started worrying about accumulated signal errors.”

“Have you made any more progress in locating Sol?”

“There are four candidates in the immediate stellar neighborhood. I’ve all but ruled out three of them—but I want to refine my mass estimates a bit further before I set a course out of this system.”

“Waiting until the last minute, are you?”

Jun Davd hooked a thumb over his shoulder in the direction of the red-rimmed world-edge that overlooked the masked sun.

“I think I’ve identified our hidden friend, though. It must have been the star they called Delta Pavonis.”

Bram tried not to show his disappointment. “Well, it’s a possible reference point, I suppose. Though the relative positions of the stars in the neighborhood will have changed a lot in seventy-four million years.”

“Delta Pavonis was almost Sol’s twin,” Jun Davd went on serenely. “It was a G-type star with ninety-eight percent of Sol’s mass. It was about nineteen light-years distant. The other nearby G stars had masses of eighty or ninety percent of Sol, except for one called Beta Hydri—that was about one and a quarter solar masses—and one other exception. So the invisible star we’re circling almost has to be either Sol or Delta Pavonis—and I think we’ve already agreed that Original Man would hardly have dismantled his own system for a radio station.”

“Or it could be an interloper. A wanderer they used.”

“In that case, the proper motion of all the nearby stars would be much greater than we’ve observed during our stay.”

“Oh, right.” Bram blushed like an apprentice. After more than five centuries of subjective time, Jun Davd could still make him feel like the little boy whom Voth had sent to the observatory to take astronomy lessons.

“The interesting thing is that the other exception is also almost a twin of Sol—a G-4 of one point oh eight solar masses.”

“So we still can’t tell which—”

“Except for the fact that it was part of a triple star system that went by the name of Alpha Centauri. Which also happened to be Sol’s closest neighbor—just a shade over four light-years away.”

With mounting excitement, Bram began, “That means—”

Jun Davd nodded. “On the assumption that stars that close might have been gravitationally bound—however tenuously—I searched for matching G stars about that distance apart, one of which was part of a triple system.” A grin spread slowly across his dark face. “They’re still there, drifting hand in hand through the spiral arms, and they haven’t changed position much with respect to Delta Pavonis, either.”

“Jun Davd, you’re incorrigible! I’ll never forgive you for keeping me in suspense like that. How far?”

“Less than twenty light-years. Boosting at one gravity, we can be home in seven subjective years.”

Home. The word had a strange ring to it. Bram slapped Jun Davd on the back. “Let’s hurry and get started, then.”

The walker, misinterpreting the slap, rose to its full height. The drover came over and said, “Are you ready to go?”

“In a minute,” Jun Davd told him. He turned back to Bram. “There’s one more datum.”

“What’s that?”

“The G star that seems to be Sol happens to be at the exact center of the sphere of radio clicks that’s growing our way. As if it were the focal point.”

“Original Man!” Bram whispered. “He has come back!”

Jum Davd shook his, head. “That doesn’t seem likely. We’ve had the longfoots in between. We may be about to meet the next contender on the evolutionary treadmill. Or Smeth may be right. It may be a natural phenomenon. In any case, we’d better go. see.”

He picked up the remaining pair of saddlebags and slung them over his own shoulder. The other walkers in the caravan, feeling the tug of the rope, struggled to their feet. In a few minutes, Bram and Jun Davd were following the swaying line of biotransports down the well-scuffed trail to the staging area.

There were plenty of willing hands at the other end to help the caravan unload. Ame was there, supervising the lashing of some bulky crates to an enormous wooden frame whose booster rockets, bolted to the corners and along the sides, must have added up to a hundred thousand pounds of thrust. Bram also spotted his son, Edard, clambering around at the top of a mountain of freight, unfurling a cargo net. Edard saw him and took a nicely calculated leap that brought him floating down to within a foot of where Bram and Jun Davd were standing.

“Hello, Father. Hello, Jun Davd. What have you got there? Documents mostly? If you have anything fragile, I’ve got room for it with my stuff. I’m riding with the supercargo this load, and I can keep an eye on it for you at the other end.”

Edard was fair and slender, with a suggestion of epicanthic folds at the corners of his eyes that must have come from mama-mu Dlors after skipping a generation. Bram was sorry that Edard had never met his partial gene grandmother; Dlors had elected to remain on the Father World. As a dancer, she had been part of the musical world, and she would have been as proud of Edard as if she had been any latter-day grandmother contributing a full complement of grandmotherly genes.

“You’re going to ride that thing?” Bram asked, casting a dubious eye at the rickety pile. “In nothing but a space suit?”

“It’s only a few hours to Yggie now, and the super’s got an extra bottle of air he’s willing to share,” Edard said cheerfully.

Ame sauntered over. “Everybody’s hitching rides now,” she said. “I’m going to ride up with my last load, too. I’m saving the delicate stuff for then.”

Edard cast a glance upward to where the silver shape of the space tree hung overhead. “Got to take advantage of Yggie’s favorable position while it lasts. Look at these mountains of souvenirs around us. It’ll be half a Tenday before we load it all, and then we’ve got to get the walkers and heavy equipment up there, not to mention packing up our own personal odds and ends.”

Bram conceded the point with a nod. Before coming down to the surface on this final trip, he had given the order for Yggdrasil’s rotation to be stopped. The tree’s inhabitants could put up with weightlessness for the few days it took to make the final transfer of goods. The swarms of cargo pallets were landing all over the branches. The limited docking facilities at the hub were being reserved for passenger vehicles.

“I’ll accept your offer with thanks,” Jun Davd said to Edard. “Here, give me a hand with these boxes of instruments. Be careful—there’s a lot of glass.”

Edard pitched in, and he and Jun Davd made a number of soaring trips in tandem to the top of the heap with boxes slung between them, while Bram unloaded the walker. Fifteen minutes later it was done. The cargo net was tied down securely over the mound of bales and crates, and the supercargo, after inspecting all the fastenings, walked all the way around the wooden platform, checking the weight distribution at intervals with a jack arrangement that lifted the whole thing off the ground.

While they waited, Bram said to Edard, “What have you got there?”

Edard’s face lit up. “Musical instruments. Hundreds of them, all gathered into one place by the longfoot archaeologists. We would never have been able to collect them all ourselves in twenty years of digging! This is my fourth load. Bramfather, the violin—and the other stringed instruments—are entirely different from the way we’ve conceived them! They had only four strings, and they were played with an ordinary manual bow, not motorized disks or powered friction wands. And the instruments themselves are beautiful, curved, complex shapes sculpted of wood. We’ll have to learn how to copy them! We’ll hear music we never heard before! But learning to play such devices well will take a lot of practice!”

“Your mother will be pleased.” Bram could not help thinking of Olan Byr, who had devoted his life to reinventing the old instruments.

“I’ve already given her one of the cellos,” Edard said. “On my last trip a few days ago. She was practicing on it when I left.”

“We’re filling in all the blank places in human culture,” Ame said. “Books of art reproductions—shelves of them. And thousands of actual paintings and pieces of sculpture from the later centuries. And holos of opera, dance, and dramatic performances. And in my field, a complete survey of terrestrial paleontology going back four and a half billion years.”

“Biology, too,” Bram said. “We have a complete DNA library of thousands and thousands of plant and animal species.” Those had been among the first treasures to be moved; they now were in storage aboard Yggdrasil.

Edard hardly listened; he was carried away by his own enthusiasms. “And musical scores! More than nine hundred compositions by someone named Schubert—songs, symphonies, quartets! He must have lived after the discovery of immortality to have written so much! And thirty-two piano sonatas by Beethoven, all of them strikingly different. I never knew he’d written so many! And operas by Mozart! Oratorios by Handel! They all belong to us again!”

“We’ll look forward to your next concerts,” Jun Davd murmured.

The super made a few last notations on a tablet with a vacuum stylus, scribbled his initials, and tacked the sheet to the pallet frame. “All set,” he said.

Edard climbed to a perch atop his possessions, got a firm grip on the cargo net, and waved. A Cuddly rode his shoulder. Bram, Ame, and Jun Davd stood well back with the caravan master and line of walkers. Flame bloomed behind the splash skirt, and the heavily laden platform lifted ponderously, seemed to hang poised for several seconds, then rose with increasing speed into the black sky.

Around Bram the tethered walkers pawed the ground in response to the vibrations. Their attendants calmed them by stroking the affected pseudoganglions. Bram followed the yellow square of flame with his eyes as it climbed toward the hovering tree.

Bram’s eyes were still turned upward when Jun Davd grabbed his sleeve and said, “Look!”

Somewhere past Yggdrasil a new star bloomed. It was a bright blue spark, moving rapidly across the field of stars. It lost its proper motion and turned brighter.

“I believe it’s a fusion flame,” Jun Davd said calmly.

The caravan master and drovers, following their gaze, gaped skyward. On the surrounding plain, activity slowed and stopped as other people noticed.

The blue spark was the brightest star in the sky. It moved not at all against the constellations now.

“They made their course correction,” Jun Davd said. “It appears that this is the disk they’ve chosen.”

“Where…” began a stunned Ame.

Jun Davd squinted at the strange new constellations that had taken shape after seventy-four million years. By now he knew them by heart. “They seem to have come from the general direction of Sol,” he said. “Of course, it was inevitable that they’d get around to Delta Pavonis sooner or later.”

“All those clicking stars…” Bram said.

Jun Davd nodded. “They had to be some manifestation of their message traffic, whether we could extract a pattern out of it or not. And they spread like a tide—not by exercising choice. Inhospitable places like red giants and the burnt-out cinders of white dwarfs, whose planets have no future. You’d think they would have skipped to a few of the more congenial stars first. And now their wave front’s arriving here, like clockwork.”

Bram drew a sharp breath. “But why now?” he said. “Why not sooner? Or later? No one’s visited the disk-worlds for over fifty million years. And just as we get here…”

Ame’s face was flushed behind the sparkling curve of her helmet. “Because it’s their turn, don’t you see, Bram-tsu!”

“Your extinction timetable?”

She nodded vigorously. “The figures work out about right, don’t they, Jun Davd?”

Jun Davd spoke without removing his eyes from the distant fusion flame. “We came back here in a multiple of thirty-seven million years—just as fast as we could after the Message reached the Father World, not counting the few insignificant millennia that fell through the cracks while the Nar remade us, and so forth. They got here in a rough multiple of twenty-six million years after the Message stopped.” He pursed his lips. “They seem to have arrived about four million years early. That’s within the limits of your timetable, isn’t it, Ame?”

“Divided by three, yes,” she said.

Around them on the booty-littered plain, people were gathering into groups, pointing excitedly at the sky. Bram knew that if he switched to the general frequency he would hear a babble of voices. A delegation of about a dozen people, spotting Jun Davd’s tall space-suited figure and his own well-worn tabard, were bouncing across the fiat ribbonscape toward them.

“Who?” Bram said. “Relatives of the Cuddlies? The collateral branch you postulated that might have evolved from the same root stock after the longfoots carried the Cuddlies here?”

“No,” Ame said. “That would have been the last cycle—twenty-six million years ago. The proto-Cuddlies missed their chance. They never traveled to the stars.”

Bram stared at the blue spark that was heading toward them. “Who then?” he said.

“We’ll know very soon,” Jun Davd said.

CHAPTER 9

The alien ship resembled a long jointed stick studded with budlike structures and a cluster of bubbles like white foam at one end. It was very large, as starships must be. It was not worldlike in Yggdrasil’s sense, but the segmented shaft was many miles long, and each individual bubble was easily a half mile in diameter.

“It’s a fusion vessel, all right, but not a ramjet,” said Jun Davd’s deep, composed voice from the screen. “They carried their fuel with them. They’re using a deuterium-helium three reaction. But there are traces of tritium from previous burns.”

Bram saw the implications immediately. “They started their trip with a deuterium-tritium reaction. And they’ve been at it long enough to have to switch fuels because of the decay of their tritium.”

He turned his eyes from the sticklike image on the portable viewscreen long enough to exchange glances with Jao. Jun Davd had returned to the tree in order to have the full resources of the observatory at his disposal, but the burly physicist had left Trist to hold the fort and returned to the diskworld, where, he said, “the action’s going to be.”

The strangers’ starship had been decelerating steadily for six days now at half a g. It had covered more than two hundred million miles since it had first been spotted approaching from the outer system. It would rendezvous with the diskworld in only a few hours—still with too much velocity, according to Trist.

Bram, waiting with Jao, had set up shop in the great sports arena, which was mostly cleared out now. A few people in casual dress moved through the empty spaces, picking over the remaining exhibits. Ame was among them, a distant figure working with a male associate to pack and label pods. Bram had sent all the junketing tourists—and everybody else who could be spared—back to the tree. He didn’t want half the population milling around where they could not easily be rounded up. Not with this new development unfolding. But Ame had refused to go. “Not on your life,” she’d said. “I wouldn’t miss this for anything. Besides, you’re going to need me, and Jorv, and all the other experts on terrestrial life.” She was right, Bram knew. Only a few hundred people remained on the diskworld, but he had seen to it that a sprinkling of specialists in the once-abstract disciplines was included.

“Yes,” Jun Davd’s voice agreed. “If they came from Sol, they’ve been traveling at nonrelativistic speeds. Tritium’s half-life is only twelve years and a bit. At the end of their first fifty or sixty years, most of it would have turned into helium three, their secondary fuel. And what does that suggest?”

Jao’s eyes glinted. “Deuterium-tritium fusion is easy. But tritium’s hard to come by. They would’ve made it back home as a by-product of their fusion reactors. Deuterium-helium three fusion’s easy, too—but first you have to accumulate enough helium three. Deuterium’s more plentiful. But I guess they’re not capable of deuterium-deuterium fusion yet. Nor of the boron fusion-fission reaction the Nar used in their early starships.”

He glanced at the bubble-and-stick image that was being transmitted from Yggdrasil’s telescopes. “So this is a very early model starship. They’re in the first stages of exploration.”

“It isn’t an exploration ship. It’s a colony ship. They don’t have enough reaction mass for a return trip.”

“But the bubbles…”

“If they ever were fuel tanks, they’re empty now. Our radar shows they’re hollow. And they haven’t collapsed, as a sensible membrane envelope would, nor have they been cast off. I suspect that they’ve been converted into environmental pods for a very rapidly expanding population.”

“They could have planned to set up reactors here to manufacture tritium,” Bram suggested. “Or mine a gas giant for helium three.”

“Except that there are no gas giants in this system. Nor oceans to extract deuterium from. All they could have known about this system is that there was mass here. And energy.”

Jao was agape, and Bram didn’t blame him. “You mean they sent a shipload of colonists out—to travel for generations and breed aboard ship—without knowing for sure what they’d find here? They must hold their lives cheap!”

“And it must follow that they hold other lives cheap, as well,” Jun Davd said hollowly.

“Jun David, what are you driving at?” Bram demanded.

“They’re closing with the disk very rapidly, and they still haven’t turned off their fusion drive. They must have seen Yggdrasil. And felt our radar probing them. They know there’s life here.”

Trist’s voice cut in, sounding harsh. “They’re going to overshoot, Bram. They’ll have to cut right across the rim of the diskworld.”

Bram was aghast. “They’d have to assume there must be intelligent life on the surface even if they didn’t care about the artifacts they’d be destroying. And they have no way of knowing exactly where on the rim we might be.”

“We’re sending them radio messages,” Trist said. “Just intelligent noises on every wavelength—number patterns and so forth. They don’t respond. It’s as if we don’t exist for them.”

“I can evacuate,” Bram said, thinking frantically. “No, that would take too long,’ wouldn’t it, with everybody spread out? It wouldn’t matter, anyway. Yggdrasil’s less than twenty thousand miles away, right in the path of destruction if the drive exhaust comes anywhere near here.”

“Yggdrasil’s safe, and so are you, we think,” Jun Davd said. “These careless strangers will intersect the rim between moons—at least five or ten million miles from your position.”

“You think,” Jao growled.

A scattered crowd had gathered on the plain, facing the point where the long straight ribbon of land vanished into infinity. About three hundred people were left on the diskworld, and virtually all of them were here in their space suits. They stood in small, chatting groups or lounged against the landing legs of the waiting shuttles. A few enterprising souls had even climbed to perches atop the spaces vehicles for a better view.

Bram was still uneasy about everybody being out in the open. His first instinct had been to keep people as far underground as possible. But Jun Davd had assured him that the alien ship was holding its course. For all practical purposes, the enormous curvature of the rim was a straight line, and even if that dreadful inferno of fusing deuterium and hydrogen three passed only marginally below the theoretical horizon, millions of miles of diskworld would be interposed between Bram’s people and death.

Not so for the Cuddlies inhabiting that distant latitude. Bram’s mouth tightened into a grim line as he thought of the slaughter that would take place in a few minutes.

The Cuddlies here certainly had no premonition of what was about to happen to their faraway cousins. Attracted by the festive atmosphere, they hung around the people, popping in and out of crevices and sometimes pulling at space-suit legs to be picked up.

“You could see it now if you were hanging in a bosun’s chair over the outside rim,” Jun Davd’s voice sounded in his ear. “It’s cutting upward from below a chord drawn between you and its point of intersection. It will rise above your sunward horizon after transit.”

“How soon?” Bram asked.

“Four minutes. If you sight along the outer edge, you ought to be able to see some lightening of the limb.”

Bram strained his eyes. Beside him, Jao, fussing with the tripod of a theodolite, straightened for a look.

Yes, the precipice edge that faced the interstellar night had gained a silvery hairline illumination. It projected a short distance as a faint straight scratch against the darkness. Where the scratch ended would be the theoretical horizon.

“Got it?” he asked Jao.

Jao struggled with the theodolite. “Just a second. Yah. Here we go.”

“One minute.”

All across the pebbled plain, space-suited figures showed that they were listening in on the circuit by ceasing their activities and becoming still. The Cuddlies, sensing the humans’ absorption, froze.

“Now,” Jun Davd said.

Where the threadlike horizon narrowed to invisibility, there was a great flare. Garish light spilled over the plain, casting long black shadows. Human figures, their reflexes slower than their helmet filters, raised arms in a delayed reaction to ward off the light.

Bram saw streaks of movement through the awful glare: startled Cuddlies popping back into their holes. When his eyes adjusted, not a Cuddly was to be seen anywhere.

The light dwindled to a point and disappeared. Moments later, a bright star rose against the inward horizon.

Except that it couldn’t be a star, because it was in front of one of the great, dully visible faces of a disk.

Jun Davd’s voice in Bram’s ear was tinged with sorrow. “The exhaust swept across one of the regions we never had a chance to send a survey team to. The one with the great elliptical bowl and the pyramidal objects rising tens of miles high on stilts. Radar echoes appeared to show a small city in the vicinity to service it, whatever it was. We thought it might be a research center of some sort.”

“I remember,” Bram said.

“There’s nothing there now but thousands of square miles of melted slag.”

Bram thought of all the Cuddly warrens that must have lain under the complex and about all the Cuddlies outside the zone of direct destruction that would be dying of radiation sickness in the days and Tendays ahead.

Beside him, Jao swore. “I was going to come back. Maybe in a couple of hundred years when we got ourselves established and could afford to lay off a little. The pyramid installation was the first place I wanted to look at.”

In the disk-filled inner sky, the artificial star seemed to slow as if it were on a rubber band. Slowly, slowly, the rim of the diskworld pulled it back.

“They’re not going to bother to go into an orbit,” Jun Davd’s voice said. “They’re just going to hang there.”

“Disposable ship,” Jao said. “Or disposable colonists.”

“A life form that just sets blindly out and goes anywhere,” Jun Davd mused, “and takes root if it can. And now, I’m afraid, they’re making their second pass to bring them to a halt over the rim. They don’t bother to think things out in advance. They’re empirical.”

The star hung over the point of the horizon and winked out. Across the narrow plain, space-suited people eddied about, and groups began to break up. A few cautious Cuddlies popped up out of their holes.

“Show’s over,” Bram said.

Back inside a sports arena that buzzed and echoed with excited conversation, Bram and Jao conferred with Jun Davd and watched on their portable screen the images from Yggdrasil’s remote sensors.

“We were lucky,” Jun Davd’s distant voice said. “One of our orbiting cameras happened to be no more than a quarter million miles from where our visitor decided to park. We’ve moved it closer in the last hour, and we’re still closing.”

People kept poking their heads into the alcove where Bram and Jao had installed themselves. It would have been hard to jam more people into the area where people were crowding around for a look at the screen. Outside, on the rocky floor of the arena, a number of people had been foresighted enough to fetch their own personal viewscreens from their quarters and slave them to Bram’s circuit, and each of these had growing knots of watchers around it.

“They’re continuing to ignore us,” Jun Davd said. “Not a peep on any wavelength.”

Bram studied the fuzzy image. The lack of definition took away the regularities that would have labeled the ship an artificial shape and made it look like a life form. A life form with a long lumpy stem whose segments swelled where they fit into each other and a living jelly of bubbles to cap it. The nodules along the shaft fostered the notion.

For a moment Bram toyed with the idea. Yggdrasil was a living spaceship, after all. Why not this? What kind of life form would look like a budding stick, and what function would be served by the gob of bubbles at one end?

Then he dismissed the thought. The thing was a machine, after all—a relatively primitive machine that generated a howling storm of hydrogen-helium fusion and probably poisoned’ its inhabitants.

“We make it at approximately twenty miles long,” Jun Davd said. “It could alight in Yggdrasil’s branches and never be noticed, but it’s still an impressive achievement for a manufactured article.”

“What are they doing?” Bram said.

“Nothing, as far as we can tell. No extravehicle activity, no electromagnetic emissions. No attempt to reorient the axis of the ship as a preliminary to achieving some sort of rational orbit. They just appear to be waiting.”

“Waiting for what?” Jao rumbled. “They sit there like that, and eventually they’re going to drift off the rim and get sucked down the side. Then they’re going to have to turn on that torch of theirs and burn some more landscape.”

“Perhaps they don’t care,” Jun Davd said.

Bram was staring at the glob of bubbles. Overmagnification had blended them into an undifferentiated mass, but despite the bleared focus there was enough mottled shadowing for the eye to appreciate them as a clump of hundreds of separate spherules.

They were hollow, according to Jun Davd’s radar echoes. Empty fuel tanks, each a couple of thousand feet in diameter—big enough to hold millions of tons of frozen hydrogen in its different isotopic forms. And there would be a complex maze of piping to skim off the helium three as it became available and store that separately, too.

Tritium was biologically hazardous. It was hard to believe that the empty bubbles had been converted into environmental pods. Jun Davd’s imagination must have run away with him. Surely no people would be that reckless with their generations.

The vague mottling seemed to shift, showing one of the globules more distinctly.

“Do I see movement?” Bram said. “Or is that just image shimmer?”

Jao grabbed Bram’s arm. “No, it’s movement.”

As they watched, one of the bubbles detached itself from the foamlike cluster and drifted free. A fine mist spouted from it.

“Chemical jets,” Jun Davd said. “They’re matching velocity with the rim.”

A hum of voices rose in the surrounding bay. “Hold it down,” Jao thundered.

“You were right,” Bram told Jun Davd. “They moved into their empty fuel tanks. If that one held tritium, there must still be residual radiation. They’d have to be desperate for expansion room.”

“The original life-support system must have been confined to the budlike structures on the stem,” Jun Davd said. “But with the fuel tanks, they’d have a hundredfold the living space in reserve, becoming available as they spilled over.”

“What kind of intelligent race,” Bram said in dismay, “would breed that unrestrainedly, with no sureties at their destination?”

Ame pushed through the surrounding press of bodies. “The longfoots,” she said. “The females had a dozen young to a litter, remember? They’ve come back.”

“Or their successors have,” Bram said. “Whatever else the longfoots were, they were a thoughtful people. That ship doesn’t look like their technology.”

“Rise and fall, Bram-tsu,” Ame said defensively. “Devolution and reradiation of species.”

On the screen, the separated globule fell with alarming speed toward the narrow rimscape. “That’s awfully big to be using as a lander, even on a low-gravity world,” Jun Davd said. “But that’s what they’re doing with it.”

“One mistake and they’ll be scattered all over the landscape,” Jao grunted.

Bram calculated spherical volume in his head. “There could be a population of thousands in that bubble. If all of the bubbles are inhabited…”

“These strangers must like to travel in large crowds and take their environment with them,” Jun Davd said. “That detachable habitat of theirs is big enough to qualify as a self-contained colony. The ship could drop more of them off here and there around the rim and leave them to fend for themselves. Then flit around the system and seed the other disks.”

“You talk as if that ship were a living organism.”

Jun Davd laughed. “If the surviving colonies grow up to build more ships like it, then it fits the definition.”

Trist’s voice cut in. “We’re getting message traffic now between the ship and the lander.”

“Radio? Laser?” Jao’s voice was impatient.

“Neither. They communicate by modulating polarized light—switching rapidly back and forth to different planes of polarization. We can’t read the signal, but it’s a signal, all right.”

“What kind of pattern? Binary, or what?”

“No, it’s positional. It codes for some kind of grid. And now that you know that, you know as little as I do.”

“Why would they modulate polarized light?” Bram asked. “If you’re going to communicate by light, there are easier ways to modulate it for a signal.”

It was Ame, unexpectedly, who answered. “Perhaps because it corresponds to their natural sensory input.”

“Now, Ame, we use radio mostly,” Jao said condescendingly. “But we don’t see by radio waves.”

“No,” she said, “but we use it the way we use visible light—by modulating its frequency. Or we use it by mimicking sound—by modulating the amplitude.”

Bram pondered Ame’s startling supposition. “But where does a positional grid come into it?”

“I don’t know, Bram-tsu. We use radio waves to build up pictures or sound. And when we use laser, we use it more or less as if it were just an improved kind of radio. It has something to do with the way they think or perceive things.”

“Trist, can you rig up something that’ll modulate polarized light?” Bram asked.

“Sure, nothing to it,” came Trist’s cheerful voice.

“Can you beam some of their own patterns back at them—just as a recognition signal? Just to get them to notice us.”

“I’ll get on it right away.”

“And get somebody working on that grid.”

“The chess club’s already taken it on as a project. So have the linguists.”

“Get them together.”

On the screen, the stick ship had moved out of the frame as Jun Davd’s remote camera followed the life-support module. It showed as a pale blob against a rim-scape that whizzed by at blurring speed.

“Looking for a spot to light,” Jun Davd said. “They had a choice of two directions. They chose yours.”

“How long before they get here?”

“At their present velocity? About two days.”

Two days later,’ the thing passed overhead, looking very large. Everybody was outside again for the passage. As it sailed by, everybody waved. A few energetic jumping jacks leaped straight up fifty feet or more, wigwagging with both hands. But the bubble took no notice. It receded into the distance, blank as an egg.

“They almost nicked one of the moonropes,” Jao said. “They’re flying much too close to the rim’s edge. And too low. The pilot’s a bit impetuous, isn’t he?”

Bram, sweating inside his helmet, hand-cranked the flywheel—mounted telescope to follow the enormous spheroid. The others crowded close to look at the photoplastic image in the visored plate at the end of the barrel.

“They’re losing speed and altitude fast,” Bram said. “They’re going to come down about two hundred miles farther on, it looks like. We’ll have them for neighbors.”

“The pilot’s braking too fast,” Jao said, squinting at the shaded image. “As if he made up his mind on the spur of the moment. Whoops! He changed his mind. He’s lifting up over that escarpment! Almost grazed it. He must be shaking up his passengers.”

Jao’s commentary may have been unjust. The huge globular object went into a long graceful glide, riding the plume of its jet, and set down with abrupt gentleness in the exact center of a flat circular feature where the plain was smooth.

“A seat-of-the-pants natural,” Bram said. “Like Lydis.”

“If he wears pants,” Jao said. “Or has a seat.”

Ame was looking thoughtful. “What do we do now, great-great-great-grandfather?”

Bram sighed. “I suppose we’d better pay them a visit.”

Everybody wanted to go. Bram fended them off as diplomatically as possible when they came barging into the bay where he was trying to work out a plan with Ame and Jao.

“The first meeting is going to be very important,” he told them over and over. “We’ll have just a few specialists, each with a job to do. We can’t take a crowd along.”

And then, of course, everybody tried to convince Bram that he or she was a specialist.

“As a sociometrician,” Silv Jaks said, getting strident, “my insight into the interrelationships of individuals will be invaluable.”

“We don’t even know if they’re human, Silv,” Bram said. “What we’re really after is a paleobiologlst.”

After she stalked out, Jao said, “That was nothing. One of the archaeologists insisted on being included because, he said, he could tell us a lot about them by studying their pottery.”

Ame wrinkled her nose. “It might not be a bad idea to take along someone from the Theoretical Anthropology group, though. It would give us some kind of benchmark for behaviors.”

“Who do you suggest?” Bram said.

“Heln Dunl-mak,” Ame said promptly. “She’s a sociobiologist. She worked with us to try to analyze longfoot society from physical clues. She’s even been studying the behavior of social insects from the old books and holos.”

“All right,” Bram said.

“And we’d better have Jorv.”

Bram hesitated. “He’s an awfully impulsive fellow. Establishing contact could be a delicate business.”

“He knows more about terrestrial life forms and their development than anybody we’ve got,” Ame said. “There’s his assistant, Harld, but…”

“I’ll keep an eye on him,” Jao said, twisting around from his console. He winked. “With a steady hand like me to keep him in line, there won’t be any trouble.”

Bram said, “I thought you’d stay here and—”

“What?” Jao gave a roar of outrage. “Who’s going to operate the equipment? I’ve rigged up a computer signboard. I’ve programmed it with an image library and everything.”

“All right, all right,” Bram said hastily. “I wish we had a linguist.”

“They’ve all gone back to the tree with their tons of books and micromedia in their own pet languages. What do we need a linguist for, anyway? Languages all either have a grammar more or less like Inglex, or they don’t, like Chin-pin-yin. And I remember my childhood Chin-pin-yin as well as anybody. And when it comes to nonhuman speech, all us old-timers have a smattering of the Small Language.” He squinted at Bram. “And one of us, if memory serves, even has a smattering of the Great Language.”

“There won’t be anything like that from any kind of terrestrial stock,” Bram said.

Jao turned back to his console. “Trist’s getting more radio traffic between the stick ship and that camp out yonder. Want to hear it?”

He turned up the volume, and a series of rapid, hard clicks came out of the speaker, like twenty people snapping their fingers as fast as they could.

“When did they switch from modulated polarized light to radio?” Ame asked.

“At about half a million miles. But Trist’s analyzed the signals. He thinks they simply reproduce the patterns of the polarized light version—same positional code on a grid. He still hasn’t figured out how the grid is organized, though. One thing’s for sure—it isn’t any simple up-and-down-and-across raster. Trist thinks it’s irregular.” Jao looked troubled. “But that’s crazy.”

Bram listened to the snapping sounds for a while. “Maybe their receiving equipment is better than my ear,” he said, “but it sounds as if those noises are coming on. top of each other—overlapping. How can they extract an information-beating signal out of that?”

“Trist’s taken the signals apart. He says he thinks they’re organically produced.”

Ame scrunched up her features. “It’s a language, then. A language where sounds have visual coordinates.”

“I don’t understand,” Bram said.

“Bram-tsu, our group’s done a lot of work on sensory impressions and perception,” Ame said. “Back during the years when we were trying to build up the new sciences. Doc Pol helped us with the medical aspects.”

“That old curmudgeon!” Jao exclaimed. “I thought he didn’t believe in anything he couldn’t tap, prod, or take a urine sample from.”

“He says polysenses are very common among human beings—much commoner than is believed. People who hear sounds as smells, for example, or who taste colors.”

“Crossed wires,” Bram said.

“No, it isn’t just that. It’s normal in all of us to some extent.”

Bram thought it over. “Like Edard reading an orchestral score and hearing the music.”

“Something like that.”

“Or Mim swearing that different keys have different textures—G-major being hard and brittle, D-flat soft and velvety. She had an argument with Ang about it. Ang said the only difference between keys is that they’re higher or lower.”

“Colors!” Jao said suddenly. “Numbers have different. colors. That’s how I remember them. Equations transform the colors. I thought everybody saw numbers that way.”

“Drugs will induce that kind of cross talk sometimes,” Ame said. “Your nervous system just happens to work that way naturally.”

Jao grinned. “Hey, Ame, what if you see flashing lights when you bump your elbow?”

“What about it?”

“Me, I get a pain in my elbow when I see flashing lights.”

Bram cut through the clowning. “So our new neighbors have a neural hookup between the sounds of their language and some sort of visual grid?”

“And they see the different planes of polarized light, don’t forget that.”

“What kind of eyes must they have?” he wondered.

“Nothing like ours. Or the longfoots. Or the Cuddlies. Or any other kind of mammalian life we know about.” She hesitated. “They may not have a continuous field of vision. They may see things as a mosaic.”

It was a very strange thought. “What would the world look like to them?” Bram wondered aloud.

“We’ll have to ask them, won’t we?”

Bram turned his attention to Jao’s screen. Jao was fiddling with images. He had made a sort of netlike structure out of green lines. The net kept stretching itself out of shape and changing the relationships between its warp and woof. It also kept trying to bend itself around various abstract three-dimensional shapes.

The snaps and clicks kept pouring from the loudspeaker. Bram could see that each one generated an orange dot within the distorted squares of the net. The showers of dots kept trying to arrange themselves into patterns within the ever-changing net.

“Are we still trying to get their attention on the frequency they use?” Bram asked.

“Yar, I’ve got a loop going on the transmitter. Trist is trying to raise their ship with the same program. Imitating their grid without knowing the coordinates is gobbledygook, but they still should extract a pattern.”

Bram shook his head. “I thought they might have tried to contact us by now. The way they set down so abruptly after their flyover of our camp.”

“We’re keeping watch from a little way up the moonrope,” Jao said, “Some volunteers set up a telescope station on top of the stalled moon car. They’ll let us know right away if anything starts moving in our direction.” He adjusted a dial. “But I don’t think they’re coming. It’s going to be up to us.”

Jorv showed up a few minutes later, impatient to start. He wore a vacuum suit with the helmet tucked under his arm. “I’ve been suited up for an hour,” he said. “When do we go?”

“Not for a couple of hours,” Bram said. “They’re getting the walkers wound up and rounding up supplies and equipment. And some of our people need time to get ready.”

That was Heln. She was putting together her material on ants, bees, beavers, wolves, rats, apes, elephants, antelopes-all the vanished animals of Earth that had lived in groups. If intelligence had evolved from any of them, their descendants would resemble them as little as man resembled the tree shrew. Heln wanted to be prepared to spot basic characteristics and extrapolate from them.

“Why delay?” Jorv said pugnaciously. “Pick up a few extra air bottles and get going.”

“Don’t you want time to get organized?” Bram countered. Jorv had nothing with him, not even a camera or a pad to take notes on.

“What for? Get a look at them, I say. Plow through the data afterward.”

Ame came around and put a hand on Jorv’s arm. “It’s not just a case of observing them, Jorv,” she said. “We’ll work from your opinions—but we have to try to communicate with them, too.”

“Why don’t you meet us at the vehicle air lock in, say, two hours,” Bram said.

Jorv walked out, shaking his head and muttering.

Bram helped Jao pack up his computer signboard and image library, while Ame went to give Heln a hand and to collect Shira, her paleobiologist colleague. Heln turned out to be a small, pert redhead, loaded down with a portable reader, cartridges, pad and easel, recorder, and other equipment.

When they arrived at the walker stables, Bram saw that only two walkers were equipped and ready for him, not the three he had arranged for.

“Where’s the other vehicle?” he asked the ostler, a squat, muscular man who was strapping a spare air tank on one of his charges.

“He took it,” the ostler said. “Your friend. Said he was getting a head start, that you’d catch up with him.”

“Jorv?”

“Short chubby fellow, sort of a restless way with him? I told him that I wasn’t finished packing it up, but he said as long as it had enough air and power on the meter to get him there, it was good enough. He almost wouldn’t wait long enough for me to put in a reserve air tank. I said to him, you don’t want to go out there without one—never mind that you’re only one person in a life-support system that’s supposed to handle three.”

“How long ago?”

“About two hours.”

Bram turned to the others. “I don’t know what he’s up to, but we’d better run him down before he gets there.”

“We’ll have to triple up,” Jao said. He looked at the mound of gear they had brought with them, then his eye lit on the red-haired sociobiologist. “Why don’t you and Ame and Shira ride together, and Heln and I can squeeze in with all this equipment.”

The walkers loped side by side across the dim plain, stretching their legs of plastic and synthetic protein. Their yellow headlamps bored into the endless ribbon of rubblescape ahead of them. They had traveled far enough so that the tethered moon was at their backs, showing its shape like a child’s top. To their right was the bloated face of a disk, casting a rusty light. To their left were the deeps of space with a hoarfrost of stars.

“Not a sign of him,” Bram said.

“Don’t forget, he’s running lighter,” Ame pointed out.

She was squeezed against him on the narrow bench. On her other side, Shira’s bony hip dug into her. The lanky paleobiologist said, “He’s had a two-hour head start. But Jorv’s not a good driver. He’ll try to hurry his walker too much, and that’ll mean that its legs will just be churning around in midair a good deal of the time.”

“Could we have passed him somehow?”

“We can see clear to the edge on either side. We’d have noticed his lights.”

“If he remembered to turn them on,” Shira said, and fell silent.

“We’ve been running for three hours,” Bram said. “We’ll be there soon. If we were going to catch up to him, we’d have done it by now.”

“Don’t worry, Bram-tsu.” Ame said. “Jorv is a very intelligent man. He won’t do anything too rash. All he wants to do is study them.”

“They may be studying him by now,” Bram said, and urged the walker on.

An hour later, the great pearly dome of the alien bubble grew out of the dimness ahead. There was no question of it appearing over the horizon—not on the diskworld. It simply became visible as a dot and grew larger.

Bram slowed the walker and approached at a trot. Jao, driving the other walker, fell in beside him.

The aliens were deploying around their bubble, queer sticklike creatures who hurried back and forth, carrying huge cone-shaped containers that they peeled open to reveal equipment and housing materials. Wheeled vehicles, whose barrel-shaped tires seemed to be clustered at one end, leaving a tubular chassis projecting with an upward cant, were being readied. All the activity was taking place under the glare of work lamps set up on tall stands around the perimeter of the camp.

“They like things bright,” Ame said, looking at the pool of light around the tremendous ball.

“Look, there’s Jorv’s walker,” Bram said.

The spindly vehicle, its bubble deflated, stood a short distance from the equipment-littered area of activity. There was no sign of Jorv himself.

“Collapsed bubble,” Bram said. “It should have reinflated itself by now. I hope Jorv’s not—”

Shira tossed her head. “If I know Jorv, he was careless about getting out, that’s all. Walked away and left it unsealed.”

“Bram-tsu,” Ame said. “Do you notice something strange?”

It struck Bram after a moment. “Yes, why aren’t there swarms of those creatures around the walker for a closer look at it? It’s just sitting there. Don’t they have any curiosity?”

“Maybe Jorv’s getting all the attention.”

“No, he isn’t.” Jao’s voice came through the suit radio. “There he is, wandering around in the middle of their camp, and they’re ignoring him.”

Bram spotted the human figure after a moment. Jorv was dawdling about in bemused fashion, pausing here and there to look at things that interested him. He might have been out for a Tenday stroll. The stick creatures hurried past him on their errands without stopping.

It wasn’t quite true that they were ignoring Jorv, though. Jorv got too close to some piece of equipment that a group of them were setting up, and one of them detached itself from the work party long enough to make a number of short, aggressive rushes at the space-suited human. Jorv scrambled back out of the way. Bram couldn’t blame him; even from a distance the rushes looked scary. Jorv kept his distance, and the alien went back to its work, paying no further attention to him.

As the walkers cantered closer, Bram was able to make out more details of the creatures. They were long, tubular beings with pipestem limbs that seemed to grow out in a cluster from just below an oversize head. They walked upright on all fours, like animated plant stands—keeping the trailing portion of their bodies from scraping the ground by curling it upward in balance.

“Our ancestors ran on all fours, too,” Shira said, mostly for Bram’s benefit. “They learned to knuckle-walk, so that they could carry things at the same time. That’s why evolution let us keep forelimbs we could manipulate with.”

“It made for the development of intelligence,” Ame agreed. “But these creatures never adapted for a two-legged gait. I wonder if…”

Bram studied the distant figures. The beanstalk creatures seemed not at all handicapped by their quadruped stance. The forward pair of legs did double duty as arms, and when the creatures carried things—tottering in the low gravity and intermittently dropping a front limb for temporary balance—Bram was amazed to see the tubelike abdomen curve flexibly around to assist with the grip. There seemed to be a clasping member at its tip.

The creatures wore enormous boxlike helmets that were far too large even for the oversize heads that could be seen shadowily within. A human child could have curled up inside.

“They want lots of room in those helmets,” Bram said aloud. “I wonder why.”

He reined the walker to a halt next to Jorv’s abandoned vehicle. Jao and Heln pulled up behind him.

“We’d better walk from here,” he said.

The five of them climbed to the ground. The pipestem figures in their unwieldy many-faceted helmets made no move in their direction. They went on with their restless scurrying to and fro, never pausing in their chores.

“Do you see what they’re doing?” Jao said, putting a hand on Bram’s sleeve.

Bram looked over to where the floodlights lit the underside of the tremendous cloudy ball that had been first a fuel tank, then an environmental module, then a landing craft.

It was growing all sorts of attachments. An undergrowth of prefabricated polyhedrons. Huge glistening balloons that were blown up and sprayed with hardening foam to become permanent structures. A network of tube-ways and covered platforms that connected with the beginnings of some kind of large excavation.

“That lander will never go anywhere again,” Jao said.

Bram nodded. “They’re here to stay. First spot they touched down on. I get the feeling it could have been anywhere on the rim. They didn’t waste any time unpacking, either.”

Heln came over, festooned with cameras and recorders. “This is all I’ll need,” she said. “I’m leaving the rest of it in the walker. I was able to go through most of the material on the way.”

“Any ideas?” Bram asked.

“I may have. First I want to see if Jorv and the others can pin down a working phylogeny for those creatures. I can tell you one thing, though.” She hesitated.

“Go on.”

“They’re not a contact species. But they observe a hierarchy of space.” She saw his puzzled look and added, “You see, it would affect their social organization—and the way they communicate.”

“You can tell all that by looking at them from a distance?”

“On average, they maintain a uniform separation between themselves of about one point five limb lengths in close working situations.” She gave a troubled frown. “The limits of fang and claw, you see. In humans, it’s about three feet. But the real clue came from Jorv.”

“You mean when he got too close to that equipment and was warned off? I suppose it shows that these beings are touchy.”

“No, not necessarily. They may inhabit a different universe of perception. Communication with them may not be a matter of language, or symbols, or images.”

She cast a glance at the folded easel of the computer signboard that Jao was removing from the walker.

“I don’t understand,” Bram said.

Heln hesitated again. “I don’t believe they’re aware of Jorv.”

“But they saw him. They rushed him till he backed off.”

“That’s not what I mean. I mean they’re not aware of him as an entity. They’re aware of the alteration of hierarchical space that his presence caused.”

Jao paused in his labors. “Just like physics,” he said. “The shape of space is defined by the presence of matter.”

Heln pursed her lips. “I know it might not seem to make much sense…”

“No, no,” Bram said hastily. “In the physical sciences we reason from a single datum sometimes and reach the most astonishing conclusions. You’ve got a new science here. We’ll take your word for it.”

Ame was anxiously surveying the scene within the floodlit area. “Jorv just got himself chased again,” she said. “We’d better get over there before he gets himself into trouble.”

“Yes,” Bram said. First he checked the air bubble of Jorv’s walker. It had deflated because the thickened edges of the gasket were misaligned. Shira had been right about Jorv’s carelessness. He must have shouldered his way out of the vehicle frontally, probably spreading the bubble’s lips apart with his hands, then letting them snap back into place. Bram realigned the closure and saw some of the collapsed folds begin to stir and rise; they might need that air on the way back—Jorv hadn’t bothered to set out with a full complement of reserve air bottles, and if he’d had to get back home on his own, he might have made a close thing of it.

Jao slung his computer over his shoulder, and Bram shouldered the folded easel. Ame, he saw, had a big pad under her arm; she and Shira relieved Heln of some of her excess equipment. Together, they danced lightly across the landscape toward the stick-people’s camp.

As they approached the lit area, two of the spindly creatures trotted by at close hand, bearing a large, lightweight construction panel between them. Their gait was three-legged, and the long tubular abdomens, with gauntleted pincers on the ends, were curled around for extra support. They were backlighted by the brilliant lamps, and through the cloudy sheaths that covered their bodies, Bram got an impression of stiff, slender, many-jointed legs. The huge boxy helmets, concealing their secrets in the reflected glare, made them look like walking packing crates.

Jao stepped forward, holding up an outspread hand, but the creatures veered off to join a work crew at the perimeter of illumination.

“You’d think they’d have stopped,” he said, affronted.

“Different body language,” Shira suggested. “Holding up a hand doesn’t mean the same thing to them.”

It sounded reasonable to Bram, but he saw Heln’s pursed lips and frown of concentration.

They moved into the light. Bram saw Jorv’s space-suited figure ahead, stalking one of the stick-creatures. Jorv approached at a crouch, the lines of his body an exaggerated study in caution. The stick-creature was half turned away, flexing its reedy legs, its sheathed abdomen twitching slightly. It let Jorv get within eight or nine feet, then, abruptly, its legs bunched like springs and it soared over his head and lit down next to a pile of construction materials, where, without preamble, it joined its fellows in putting up one of the polyhedral structures.

Jorv straightened up, every line of his body showing disappointment, and began stalking another one of the creatures.

“We’re not even going to get that close to one,” Jao grumbled.

Every time Bram and his party seemed about to intersect the path of one of the creatures, it veered off and ignored them.

“Just hold on,” Bram said, “and we’ll be in the thick of them.”

“I’m insulted,” Jao said. “Am I invisible, or what?”

Heln said, “They see you … but they don’t see you.”

“Maybe they’re some kind of hive creatures,” Shira put in. “No real intelligence. The intelligence is in that bubble they landed in.”

“They’ve got intelligence,” Bram said. “If intelligence means handling tools and machinery.”

Then, without warning, they were upon one of the creatures. It reared up in their path, the light shining full on it, and for the first time Bram got a good look at what was inside those cagelike helmets.

Its face was the stuff of nightmares—two bulging domes of jelly on either side of a masklike bulb that was split by a vertical cleft. Each of those jellied eyes—if that’s what they were—was the size of a man’s head.

The cleft parted in a hideous vertical smile that hinted at something spiny and complicated within. There was a flicker of movement in front of the ghastly face—and in a moment of startled disbelief, Bram saw why the creatures needed so much room in their helmets.

There was a separate pair of limbs within the helmet!

They grew out of the creature’s face, or the sides of what passed for a neck. They were smaller manipulating limbs—shorter than a man’s arm—and these peculiar beings kept them folded up on the floor of the helmet, like a person resting his elbows on a table.

The creature swiveled its complicated head as if looking for a way of escape, and the facial limbs lifted and swung with it.

A flash of crazy thought went through Bram’s head: It must cramp their style to be deprived of the use of their grasping members whenever they wear space suits! But the creatures’ anatomy gave them no alternative. Limbs projecting through sleeves in a smaller helmet would have immobilized their heads.

Or maybe they simply needed to have their forelimbs available for grooming or self-care. Maybe they would have felt uncomfortable having the limbs enclosed apart from their faces. Bram could sympathize with that—hadn’t he suffered the agony of being unable to scratch an itchy nose while wearing a space suit?

Everything had happened in an instant. Through his radio Bram heard a couple of people gasp—he felt like gasping himself—and then the jelly-eyed horror spun around and galloped away.

“It saw us,” Jao said. “I swear it saw us that time.”

“No,” Heln said. “It saw the effect we were having on its visual field.”

“What’s the difference?”

“Have you ever heard of an animal called a frog?”

“Huh?”

“Wa, in Chin-pin-yin. The children’s story about the mandarin who turned into one.”

“Oh, yar.”

“It saw motion, not objects. It ate an animal called a fly, but it didn’t see the fly until it moved. If you tried to feed a captive frog on dead flies, it would starve to death.”

“Are you saying that these tomato-eyed beasts are frogs?”

“No,” Heln said patiently. “I’m saying that they have a queer sort of brain wiring that enables them to cooperate as a species but that makes other life forms irrelevant to them—as irrelevant as a fly is to a frog … until the fly moves. We’re no part of their experience—or their instincts—so we don’t exist for them.”

Bram looked around at the teeming campsite. “Aren’t you overstating the case? These aren’t primitive animals. They’ve got space travel. They must process information somehow in those heads of theirs. Can you have intelligence without curiosity?”

Something was bothering him. It was Jao’s description of the creatures as “tomato-eyed.” It was true. The eyes were reminiscent of gigantic green tomatoes. A memory nagged at Bram somewhere below the level of consciousness.

“Maybe.” Heln stood her ground. “And maybe you can have intelligence without empathy. Maybe we’re going to find that these new neighbors of ours lack basic empathy-that it’s literally impossible for them to relate to any life form but their own.”

“That would certainly make it hard to communicate with them,” Ame said with a strained smile.

“To say the least,” Bram said.

“I hope not,” Heln said, shifting some of her technical accoutrements on their carrying straps. “There has to be a way for us to plug ourselves into their sensory wiring. We’ll just have to find it. Let’s hear what Jorv has to say. Maybe he has some ideas about their phylum by now.”

Jorv saw them coming and ambled over to greet them. He seemed preoccupied. “They may be descended from terrestrial insects,” he said without preamble. “Did you notice those wraparound eyes? They probably carry the efficiency of the compound type of eye as far as it can go—their visual acuity may surpass our own. And the muscle attachment—I wish I could make out more through those space suits. They don’t move as if the muscles were operating proper skeletons!”

Bram tried a mild reprimand. “Jorv, you shouldn’t have come out here on your own. We may be running up against a very queer situation.”

“Queer? I’ll say it’s queer. They won’t stand still long enough for me to get a good look at them. Did anybody bring cameras? Ah, Heln—you’d better start taking some pictures.”

“Did you try to talk to them?” Bram asked.

“Talk? They won’t talk. Ame, I think you may have hit on something when you deduced a hookup between sensory input and a visual grid from their radio signals.”

Ame looked excited. “The compound eye means there’s no overall image—just a very large number of separately perceived patches. The visual information jumps from facet to facet, whether the object is moving or the creature’s head is moving, and the sum of the signals is processed somewhere in the brain—”

She broke off. Everybody looked at Heln. “Your frogs,” Jao said.

“What have frogs got to do with it?” Jorv said irritably. “These are insects!”

“Very big ones if that’s true,” Shira murmured. “Insects shouldn’t be able to grow to that size, with exoskeletons as a limiting factor. And they were lungless, weren’t they? They transported oxygen through tracheae. That would limit their size, too.”

“We won’t know till we examine one!” Jorv’s eyes were gleaming. “Do you think you could help me get one back to our camp?”

“Sit on him if you have to,” Bram told the three women. “Jao, let’s get your computer signboard set up.”

They worked at it for fifteen hours, taking turns going back to the parked walkers to replenish their air supplies and to fetch various items that Heln or Jao had brought along in hopes that they would help.

Nobody ate a lot during that time—just a few hasty handfuls of travelfood that had been included with their rations—and nobody slept at all, despite the fact that all of them had been awake for more than twenty-four hours.

They got nowhere.

Every once in a while one of the stick-beings would dart over and pause for a look at the computer display or at an earnestly semaphoring human being. At least they seemed to be looking. But they always trotted on past without showing any reaction.

Once an exasperated Jao had stepped squarely into the path of an ambulating beastie and attempted to herd it with blocking movements of his wide torso toward the little communications arena. An observer could not have said that the intercepted individual exactly tried to evade Jao. Simply, it was somehow past him without appearing to have noticed his presence.

It was a pity, because Jao had knocked himself out to prepare his visual displays. There was a beautiful sequence in simplified diagrams and actual images that showed the human itinerary from the Whirlpool Galaxy to the Milky Way to the vicinity of the enclosed star that was presumed to be Delta Pavonis. Another sequence ingeniously arranged as a query showed the presumed progress of the tomato-eyed strangers from a presumed Sol.

Jao never got anywhere near to unveiling his masterpieces—a sophisticated scenario that showed the ancient origin of humankind on a planet of Sol, showed bright schematic images of DNA, and showed the diskworld itself with stylized radio waves spreading from it toward the Virgo cluster of galaxies. It went on to show the Whirlpool in the Canis Venatici cloud, halfway to Virgo, being bathed in the radio waves, the reemergence of the colorful DNA schema, then the recreation of human beings and their return to the planet that had given birth to their genes.

“They don’t take visual information!” Jao said in disgust. “And them with eyes as big as my head!”

“It’s not visual information, it’s abstractions,” Bram said. “Let’s show them something closer to home.”

They displayed images relating human figures to Yggdrasil, with much pointing at the green blob that could be seen over the horizon. They showed the fuzzy images of the stick-ship and finally life-size holos of the jelly-eyed creatures themselves, played back from Heln’s camera.

But when Jao projected one of the fearsome holos in the path of one of the trotting creatures, it passed through it without pausing. “It didn’t see the image as real,” Ame said. “Not polarized for their eyes.”

“But sometimes they do seem to pause for a second and show body reactions, particularly with the moving images,” Shira said, sounding frustrated. “And certainly when we get too close to their precious equipment.”

“The same way your feet find stepping-stones when you cross a stream,” Heln said. “Doesn’t mean you’re really aware of the stones.”

Heln, tree-born, had never seen a stream and certainly never had crossed one on stepping-stones, but Bram appreciated the aptness of the simile.

“Going to try just one more thing,” Jao grunted.

He generated an animated image of a Cuddly, and the next time a stick-creature intersected their little communications arena, he sent it scampering toward the being.

The alien being stopped dead in its tracks and stood stock still for all of two or three seconds. For a moment Bram thought it was going to rear up and change direction, as it did when a human got in its way. The nightmare face seemed to expand as the central cleft widened, and Bram thought he saw a flicker of movement within the cavity.

Then, apparently, the creature dismissed the holographic Cuddly and darted off on its interrupted errand.

“We almost had it that time!” Jao exclaimed. “Did you see that?”

“But why?” Shira asked. “It couldn’t have seen the holo as real.”

“Something in its neural circuitry reacted,” Heln said. “Something about the image almost tripped a switch.”

“But what?” Bram wondered. “The Cuddly’s size? Its movement? Its resemblance to something it is primed to react to?”

“Maybe all of that,” Heln said. “But it shows that the switch is there, ready to be tripped. And maybe after we get back and have time to study our film and data, we’ll be able to figure out how to get them to notice us.”

They kept at it until their margin of reserve air was almost gone. And then they had trouble prying Jorv away. “They’re insects, all right,” he babbled happily. “Or at least in the insect line of descent. It’s all there in the jointing of the legs—the two short basal joints, femur and tibia meeting at the knees, then the three short joints and former claws of the tarsus. I’d give my eyeteeth to see them out of their space suits.”

Bram had Jao drive Jorv back; he didn’t trust the pudgy zoologist not to return to the alien campsite. Before they entered their separate vehicles, Bram exchanged a few words with Jao.

“Did you notice there were no Cuddlies hanging around? That’s odd … there must be a few burrows in the area, and they’re such curious little beasts.”

“Huh? They’re probably just being cautious till they figure these insect-people out.”

“Heln says that maybe we’ll be able to figure out how to trip that switch in their brains after we learn why they reacted to a Cuddly image.”

“What are you getting at?”

“Maybe we won’t want to.”

It was hard for Bram to keep the curious from sneaking out to the insect-people’s base camp. “Not until we know more,” he insisted. “The specialists are working on it. We don’t want to take the chance of stirring them up till we have some chance of communicating with them.”

In the meantime, Yggdrasil was drifting inexorably farther away. Smeth called several times a day to display fits of ill temper.

“We were supposed to leave this system within two Tendays from now. Jun Davd’s got our course worked out for that window, and my black gang’s warming up the fusion drive. We’re halfway through our checklist. We’ve already got a starter ball of deuterium slush in the throat of the scoop, and it’s evaporating with every second that goes by.” His words became a wail. “And where’s Ame? She was supposed to be back here days ago! The twins are acting up, and I don’t have time to handle them by myself.”

“I’m sorry,” Bram said. “I couldn’t get Ame to leave now if I tried.”

“Well, it’s not every day you run into a new intelligent life form,” Smeth said grudgingly.

“I can’t get anyone else to leave, either,” Bram told him. “We may have to change our plans. We can’t leave this system without knowing more about what’s waiting for us at Sol. We may not own it anymore—not if these are the new inheritors.”

“If we don’t pack up and go soon, Yggdrasil will have to make another circuit. It would use up our whole starter ball. We could be delayed another year.”

Bram broke it to him gently. “I think that’s what it may take. We’re going to have to put it to a vote.”

“Don’t say that! Jun Davd spends all his time looking at the pictures and data you sent up. I’ve been trying to get some revised escape orbits out of him, but his computer’s all tied up with an analysis of the radio traffic that—that colony sent.”

“Sent?”

“Yes, it’s stopped. They don’t seem to have anything more to say to one another. Jun Davd says the colony’s on its own.”

“Is he getting anywhere with his analysis?”

“No.”

Jun Davd was interested in Heln’s theories. “A life form that lacks basic empathy on a neurological level. It’s a chilling thought for us humans. Very frustrating. Our only other relationship with intelligent beings was with the Nar—probably the most empathetic life form in the universe.”

“I’ve forbidden our people here to go visit. But I know they sneak over there anyway, make a party of it. Walkers are checked out and are gone for twelve or fifteen hours. I can only hope they’re watching from a distance. The insect-folk themselves are sending out pickets. Those wheeled vehicles of theirs are spreading outward in reconnaissance patterns. They’re probably looking for expansion sites. I hope there are no encounters.”

“And if there are?”

“According to Heln, they’ll see the human beings as a detail of their environment. An unimportant detail. Irrelevant.”

It was an audio-only circuit, but Bram could almost see Jun Davd shake his head in bemusement. “What if some impatient idiot grabbed hold of one of these creatures?”

“Then he’d be a relevant fact of the environment. That’s the kind of encounter I don’t want.”

“I hope your terrestrial life specialists come up with some answers soon. People here in the tree are agog at your pictures. We can’t keep them penned up much longer. You’re liable to have tourists.”

Bram groaned. “That’s all we need.”

“Heln believes that there may be a switch in the neurological makeup of these insect folk—a switch that would make us a part of their perceptions—and that this switch can be tripped if we find the key?”

“Correct.”

“And that once tripped, it will stay tripped for them as a species?”

“Yes.”

“Extraordinary!”

“Heln’s delved into volumes of biological lore from the buried libraries and says there are all sorts of examples of these neurological switches—they’re called ‘releaser’ mechanisms—in terrestroid life. If the animal’s nervous system is complex enough and there’s a degree of social organization, the perception of the triggered individual becomes the perception of the species.”

“What if the perception is something we won’t like?”

“All we want to do is get them to notice us.”

“Be careful.”

“I’m on my way to see Jorv now, to see if he’s made any progress in tracing their species.”

“The claspers at the tip of the abdomen were characteristic of many insects,” Jorv said happily. “Like paired forceps. Insects developed an opposing grip before our own ancestors did. Only they had it in a different place.”

He looked up at Bram, pleased with his little joke. Jorv had gotten an artist to prepare diagrams from Heln’s pictures, and these were spread out on easels around him.

“Odd place for a hand,” Bram said.

“Not when you consider the purpose.”

“Which was?”

“To assist in copulation.” Jorv licked his lips. “A useful accessory, particularly for species that mated in flight.”

“These creatures don’t have wings.”

“No, but I’ll wager an autopsy would show vestigial wing muscles, just as human beings have vestigial tails. They lost the wings somewhere along the way, as ants did.”

Jorv pointed at a picture tacked on the wall, showing a spiny, many-legged creature with fearsome jaws—a blowup from one of the old texts he and Heln had been delving into.

“Are they ants?”

“No. I haven’t been able to find a form they correspond to—not yet. There’s something puzzling about them.”

Bram looked again at the diagram of the abdominal claspers. They were heavily gauntleted, but their form was plain enough, as a gloved hand is.

Jorv continued happily babbling. “The female claspers for gripping the male would have been in a different abdominal segment, but that doesn’t mean anything. The structures would have been there embryonically, and if evolution decided they would make a useful hand, a similar appendage could have developed from the ovipositor.”

“Ovipositor?”

“For laying eggs. It was generally equipped to puncture holes in mud, vegetation, or some other hatching medium. Living flesh, I’m afraid, in the case of some of the nastier species.”

“Insects seem to have been a remarkably single-minded life form.”

“In the sense of a will to survive? So were our own ancestors, no doubt. But those creatures building their city out there have developed intelligence. They’ve learned how to survive and propagate through technology. Don’t worry. Once we get a key to their developmental patterns, we’ll find a way to communicate with them.”

“I hope so.”

Jorv frowned. “I still haven’t decided whether their ancestors were plant eaters or meat eaters. The mouth parts are hidden inside that odd facial structure. There were over a hundred million species of insects, and so far I haven’t been able to find anything like it.”

Ame came over with a new sheaf of blowups. “Hunters or browsers?” she mused. “It would be nice to know before we meet them again.”

As it happened, it was the insect-folk who made the first move. Bram was having a meal with Ame when he got a call from one of the watchers he had posted on the plain.

“Bram-captain, one of those tube machines is rolling in your direction. It zigzags a lot, but there’s no doubt about where it’s headed. It should reach the digs in about an hour.”

“Thanks. Stay where you are. Keep an eye out for any more of them.”

He stood up. Ame said, “I’ll get the others.”

“Tell them to keep their distance till we see what they’re up to. Let’s see what they have in mind, for a change.”

He deputized a dozen people for crowd control. “Tell everybody to stay out of their way. Don’t interfere with them. If any approach is made, it will be done by one of the specialists.”

An hour later, the excavated streets were full of waiting people. Word had gotten around fast. They sat on ledges, hung over the low rooftops that had thrust themselves out of the rubble, and loitered in the stone arches. Bram had a vantage point from the top of one of the buildings facing the moon plaza. If the insect surveying party kept to the avenues of rubble leading into town, this would be the major route.

“There it comes,” Jao said beside him.

A tiny shape appeared in the distance and soon resolved itself into one of the tube vehicles, bumping along on its fat tires at about twenty-five miles an hour. The four barrel-shaped rollers were all grouped close together under a cab that seemed to carry most of the weight; the long, slender cylindrical body tilted upward at a thirty-degree angle behind it, doing a lot of vibrating. Bram supposed it made as much sense as any other design for rough country; if the cab had to crawl over an obstacle, the projecting section had plenty of leeway to tilt downward without dragging.

The bizarre vehicle rolled by the crystalline shafts of the moonropes without slowing down and came to a quivering stop at the edge of the wide plaza. Bram could see human figures peeking at it from around corners.

He waited for a door to open, but none did. After a few minutes a boxy helmet emerged from the end of the tube, about twelve feet above the ground. The rest of the insect-person extruded itself, hung rigidly horizontal from the lip of the tube by the claspers at the tip of its elongated abdomen, and let itself drop lightly on all fours to the ground. Seven more of the creatures followed.

They stood around, conferring with twitching movements of their long sterns. Bram saw little, discreet flashes of lights from their helmets and assumed it was the polarized light version of radio communication. After getting everything settled to their apparent satisfaction, they slung equipment over their humped shoulders—or hips, if that’s what they were—and began skittering down the long boulevard with lots of nervous, darting side trips, staying in a loose group.

People began to drift down from rooftops and emerge from side streets to trail after the insect-people at a respectful distance.

“We’d better get down there,” Bram said.

He vaulted over the rooftop and floated to the ground, with Jao close behind him. He strode in thirty-foot bounds across the plaza and caught up with the little parade going down the avenue.

Trouble started almost immediately. A skylarking fool who had been leaping up and down in great swoops shot fifty feet into the air and came down squarely in front of one of the insect-people. Apparently he got a good look at the jelly-eyed face within the helmet, because he backed away with a jerk and stumbled.

The insect-being showed no signs of-stopping, and the skylarker showed no signs of getting out of its way. Jao reached the spot in one long soaring arc and snatched the offending person out of the way with a hand hooked into the webbing of the life-support backpack.

He bore his kicking prize to Bram. He did not set the fellow down on ground, but held him out to Bram at arm’s length.

The face within the helmet was that of a junior archivist named—Bram rummaged in his memory—Alb something-or-other. Alb was less than thirty years old, having been born in the heart of the Milky Way, and hadn’t lived long enough to develop good sense.

“Put him down,” Bram said.

Instead of letting go, Jao rammed the errant archivist into the ground with some emphasis. Alb stood there with a silly grin on his face.

“Alb, I thought I told everybody—” Bram began.

“He can’t hear you,” Jao said. “He isn’t tuned in to your frequency.” He made twisting motions to get the idea across to Alb, but the young man just stood there stupidly, no doubt listening to the gibes of his own circle of friends.

“Oh, chaos take it!” Jao exclaimed. He dialed through his own frequencies till he hit Alb’s. He must have turned the power full up, to judge by the way Alb flinched. Somewhere out there a number of other people must have acquired an earache too. Jao proceeded to give the unfortunate fellow a dressing down. Bram tuned in for the tail end of it: “…brains of a three-legged baggage walker!”

Alb gave Bram a sheepish apology and promised to behave. Bram heard group laughter on the frequency, and Alb turned pink.

They caught up with the insect patrol some distance down the avenue of rubble. Jao’s lecture seemed to have had good effect; the trailing crowd of people was hanging back farther. One of those who wasn’t lagging behind was Heln Dunl-mak. She skipped ahead of the alien party, just beyond what she had described to Bram as the insect-people’s “avoidance zone.”

Heln’s slight figure was top-heavy with improvised equipment—a bulky pack that Jao had put together for her. It was flashing modulated polarized light, some of it drawn from frequently appearing patterns in the stick-ship’s early radio transmissions, some of it repeating and stringing together “phrases” that the darting aliens were blinking at each other.

“Best program I could cobble together at short notice,” Jao said apologetically as he waved at Heln’s dancing form. “Heln doesn’t really know what she’s saying to them, but she can punch in a few crude menus based on their physical behavior, and the computer can try to correlate it with what they’re flashing to each other at the time. Then it runs through all the combinations. With luck, we’ll get a ‘turn right,’ or ‘follow me,’ or ‘look at this.’ It’s up to Heln to recognize a response.”

But there was no sign of recognition from the insect-folk that Bram could see. By stretching his imagination to the limit, he might at best have concluded that they showed a sort of irritation or brief annoyance—analogous to what a human might display if a light were flashing in his eyes or if he were trying to talk with a radio on in the background. But such distractions, really, were below the level of awareness.

“The computer’s learning all the time,” Jao said defensively. “Sooner or later it might hit on something.”

“What you’ve done is amazing,” Bram assured him.

Jao brightened. “Want to know what the hardest part was? It wasn’t the program. It was inventing the gizmo to recognize the polarization through different planes of orientation, then to transmit the same way. That’s what takes up so much room in the backpack. I had to scavenge the faceplates of a whole bunch of helmets to build it.”

Heln, arms spread low, purposely penetrated the avoidance zone and dropped to one knee, then danced back as the creatures showed restlessness. Her equipment blazed a signal that looked sustained to human eyes but that to the aliens, of course, would have flickered. Bram saw the shadowy facial limbs lift as if to ward off something, but the creatures never stopped their prowling movements.

“They still don’t see it as speech,” Jao said. “Something missing.”

“Very frustrating,” Bram said.

One of the insect-people was using an odd camera—a sizable box with one curved face studded with thousands of pinhole lenses. It took its pictures by sweeping areas of the ruins in short arcs.

“Multiple fixed-focus lenses,” Jao said. “Motion shifts the pattern. They must have some way of reading the result. Like Heln said, it’s the way they see.”

“They’re not much interested in the people,” Bram said. “Or individual objects. They seem to want fields of view.”

“Looking for another place to light,” Jao said. “The digs here are ready-made of them—honeycombed with chambers connected by a tunnel system.”

“No,” Bram said. “We can’t allow that. We’ll be coming back here someday. We’ve got to talk them out of it.”

“First we’ve got to find a way to talk to them.”

The insect-people spent the next few hours exploring, completely ignoring the holiday crowd that tagged along. After a while, Bram became aware that their seemingly random forays added up to an extremely efficient search grid.

Besides the camera, whose purpose was obvious, they used a number of other instruments. One was a long stinger that came out of a cylinder on legs and penetrated the ground to a depth of—Bram estimated by counting the telescoping sections—thirty feet, at least. The tripod gave a little jump when it hit bottom. “Their version of a thumper,” Jao said. “They’re searching for cavities.” Other instruments, with a little thought, were soon recognized as a surveyor’s transit and a range finder, adapted to the peculiar insect vision.

The creatures seemed to get restive after a while, and after they had darted at one another in a series of little mock attacks, they all filed back to their vehicle, launched themselves up into the end of the angled tubular chassis, and disappeared inside. Bram waited, but the barrel-wheeled vehicle showed no signs of starting up.

Heln sauntered over. “Lunch break for them,” she observed. “Or some kind of break. Whatever it is, they’ve got to take off those helmets to do it.”

After twenty minutes passed, the creatures popped out of the end of the tube again and resumed their mysterious activities. Several of them could be observed preening their nightmare faces. Jorv appeared with an assistant, who took more pictures.

At the end of another couple of hours, the creatures found the ramp to the parking garage under the sports arena. This seemed to excite them. There was another head-to-head conference, with eight long tail sections sticking out and wobbling, the gauntleted claspers working convulsively.

They knew about air locks. Afraid that they might damage the locks leading to the stadium interior, Bram had been about to order that the creatures be let through while someone held the door, but one of them figured out the human machinery at a jelly-eyed glance, and they swarmed inside. They even closed it behind them.

They seemed to be awfully good with machinery.

“They can notice inanimate objects,” Bram puzzled, “but not a crowd of people.”

“You don’t understand,” Heln said. “We are inanimate objects.”

“Yar,” Jao said, as if he were an expert. “We haven’t impinged on them.”

A thought struck Bram. “They must have seen the shuttles parked in the field on their way through. If not man, then man’s works! Why didn’t they take an interest in those?”

“Held no meaning for them,” Heln supplied. “Wasn’t important. Not like the air lock here. They wanted to get inside.”

Bram spoke to his traffic control-deputies. “Keep the mob outside. I won’t evict anyone who’s already in there, but I think we’d better keep the numbers down.”

Without their space suits, the creatures from Sol were an unnerving sight—spiny legs, globular green eyes, and hard shiny integument bristling with stiff hairs. The four-fingered claspers at their projecting rears were pincers of horn, and the forward manipulating limbs, now revealed, were all tweezers and hooks.

They prowled the floor and balconies of the chamber, taking no more notice of the gawking humans than humans would have taken of moss on a rock. With the boxy helmets off, the clicking noises they made to each other could be heard like a high-speed rattle of broken sticks.

Their insect ancestry was fully apparent. “You see,” Jorv said ecstatically, “how evolution modified the exoskeleton in a way that permitted them to grow to size. It became a partially embedded, hinged, mostly external skeleton that operates as a system of levers. The extensor and flexor muscles operate separately, bridging the hinges on opposite sides.”

The skeletal apparitions gave everybody cause to remember their childhood ghost stories in Chin-pin-yin; the word for a foreigner was, literally, a “bones-outside,” and now Bram heard people around him starting to call the Earthlings that.

Jorv could hardly contain himself. “You see the pulsating of the abdomen? I think they breathe through their anus. I wonder what evolution gave them in place of lungs.”

“What are they?” Ame asked.

“I don’t know,” Jorv said. “They may have been aquatic. In that case—”

He was interrupted by a chattering Cuddly that skidded to a stop in front of the group and climbed up the nearest person to reach the shelter of human arms. The person happened to be Ame, who petted the fluffy little beast and cooed, “There, there, nothing’s going to hurt you.” The Cuddly had ventured too close to a prowling insect-thing and had had second thoughts about approaching it.

The insect-beings, in fact, had quite an audience of Cuddlies by this time. When the strange creatures had arrived and shucked their space suits, the couple of dozen Cuddlies that normally mooched around the chamber looking for handouts had immediately disappeared. After a while, when nothing much happened and the human beings seemed unconcerned, a few cautious little furry heads had popped up.

Now the Cuddlies were getting bolder. One fat little creature sat up on its haunches and scolded an insect-being that had paused, for a moment to survey the arena floor.

“Isn’t that cute?” Ame said. “It wants the bones-outside to pay some attention to it.”

“If we can’t get their attention with computer displays and polarized light, there’s not much hope for a Cuddly,” Shira said.

The little beast hopped closer and chittered more loudly.

“It’s getting awfully close to the avoidance zone.” Heln frowned. “I wonder…”

“I think the thing’s showing some reaction,” Jao said.

The face-legs, liberated from their box, swung idly to and fro. There was something about the stick-creature’s stance. It seemed to lower itself a few inches and become utterly still.

Encouraged, the Cuddly made another little hop forward.

There was a blur of motion so fast that Bram saw it only as an afterimage. The masklike face of the alien split vertically, and a long scooplike lip tipped with teeth flicked out and captured the little furry beast.

The hinged lip, longer than a man’s arm, snapped back, bearing the ensnared Cuddly to a barbed mouth. There was a single high-pitched squeal, and then with two crunches, the Cuddly was gone. The lobes of the toothed structure folded over to become a mask again.

The hum of human conversation in the chamber stopped abruptly. People stood frozen. Every Cuddly in sight streaked for a hiding place and disappeared. The insect-being stood preening itself with its hooked facial limbs. Its fellows paused in their rambles and turned their jelly-domed heads in its direction.

In the stunned silence, Jorv stood with dropped jaw, breathing hard. Suddenly he exclaimed, “Odonata!” and before Bram could stop him, he stepped up to the immobilized creature for a close look at its face.

There was another blurred movement as the creature seized Jorv with its facial limbs and bit his head off.

A woman screamed. People came out of their trances. The creature calmly continued crunching its way through Jorv’s neck and shoulder. Jao grabbed one of the picks that the archaeologists had left lying around. Bram found a steel pry bar. Several others joined them, and they ran to recover what was left of Jorv’s body from the leggy horror that was chomping its way through it.

It wouldn’t let go. A couple of men had Jorv’s body by the feet and were trying to pull it away. Bram grabbed the creature by one of its facial palps and tried to lever its jaws open with the pry bar. A hooked leg came up and raked him across the ribs. There was a sound of ripped cloth and a searing pain, but he held on. Jao swung his pick handle and smashed one of the bulging green eyes.

Even then it wouldn’t let go. It rotated in injured circles, still munching, lashing out at the struggling men with its barbed legs. The long abdomen whipped around and a man screamed as its horned pincers tore at his flesh.

Bram went berserk. He beat at the armored hide with his steel bar while Jao, grunting, labored with his pickax at the ruined jelly of the head. The thing refused to die. The limbs slashed blindly at the air. But it dropped its grisly meal, and the long toothed lip struck out again and again, looking for prey. Finally someone got a sharpened pole—one the diggers used for soundings—and ran the creature through, repeatedly, till it stopped moving.

Bram stood wearily, drenched in blood and gore, holding the slippery pry bar. He couldn’t tell how much of the blood was his own and how much had spilled from Jorv.

Shouts and screams echoed through the huge arena. The other insect-creatures, as if by a common signal, had gone on the attack. On a high balcony, the tragedy of Jorv was repeated as a stick-being pursued a fleeing woman and caught her with its facial snare. People came running, too late, to her aid. They beat and stabbed at the creature with whatever came to hand. One of the rescuers was flung away, disemboweled by a stroke of a hind claw. The tattered body tumbled slowly through the air toward the distant floor below.

Elsewhere, one of the spindly horrors ran at a group of people and emerged with a screaming victim in its mouth. It ran off with its prize, munching as it went, dropping a trail of arms and legs behind it.

Two more of the insect-beings bore down on the group of shaken people gathered around Jorv’s headless body. They were a terrifying sight, but no one ran. An extensible lip shot out and clasped someone’s leg in its prehensile hooks, but two quick-witted people threw themselves on the victim and prevented him from being dragged back. Men and women with poles, shovels, axes—anything that could be used as a weapon—converged on the monster from both sides. It loosed its grip, leaving a mangled leg that would have to be regenerated if the victim lived, and swung its three-lobed head at its tormentors. The lip raked across one victim, tearing flesh, and another man went down under the onslaught of the barbed head-legs. But other people harried it from behind, and when it swiveled its killing apparatus around to deal with them, a brave woman with a pole leaped high into the air and jabbed at a globular eye from above.

Meanwhile Bram saw the other creature rushing straight at him. The facial limbs were already extended for grasping. He knew he would be no match for the lightning thrust of the feeding apparatus—it surpassed his reach, even with the iron bar in his hand.

He dropped the bar and wrenched one of the heavy display tables from the ground. He put his whole back into it, swiveling from the hips. It was a massive piece of rough carpentry, twelve feet long, laden with rock and metal fragments that the archaeologists had not bothered to pack up. In the infinitesimal gravity, he could have lifted a weight ten times as heavy, but speed was the problem, and he needed all his muscular strength to overcome the inertia.

The table became his shield as the creature’s lip struck. There was a sound of splintering wood, and Bram felt himself being driven back by the thrust. A rain of jagged stone and metal pelted his adversary. Bram shoved back, hard, and the weight of the table helped him; his feet were braced against the ground, while his opponent, losing contact, clung to the table as Bram ran it at full speed into the wall.

Three or four people ran to help him keep the creature pinned against the wall while somebody finished it off with an ax.

They stood around panting. “We’re monkeys, monkeys,” Ame sobbed beside him, and he became aware that she was one of the people who had helped him keep the creature pinned. “I thought we were human, but we knew in our bones how to gang up on them.”

“All the rocks and junk confused it for a minute,” Jao said. “Just long enough.”

That gave Bram an idea. “Throw things at them!” he shouted.

The carnage on the floor was terrible. The insects had better reach with their legs and facial snares than the humans did with their shovels and axes, and they were very quick.

Jao was the first to react. He scooped up an armful of archaeological detritus from one of the big tables and sent a hail of missiles at another of the spindly creatures that was heading in their direction. It veered off. A sharp fragment caught it in one eye. Its lip shot out reflexively to find an enemy.

People were quick to get the idea. There were plenty of sharp objects to throw: shards from the long tables, cast-off equipment, and rubble from the floor itself. A barrage of missiles peppered the creatures from ground level and pelted them from the balconies. They came from all directions, thunking into the stiff hides, finding pulpy spots. There was no way for the creatures to avoid them, as marvelous as their eyesight was and as quick as their reflexes were. Every time they made a dash at a group of people, they were met by a volley of hurled objects.

Not that they were always turned aside. Sometimes they barged into a group, knocking people over and lacerating them, and carried someone off. They seemed to have no concept that they were outnumbered.

And then some brainy person reinvented the spear.

It was only a kitchen knife lashed hastily to a pole, but its-owner—maybe losing his nerve about running it into an enemy personally—flung it at an insect-thing as it passed him. The blade hit a soft spot, and the creature ran by with the pole sticking out of it. Another person threw another improvised pike, then everybody who had a sharp stick seemed to join in. The wounded creature began to run in circles, snapping at the skewers in its hide, then grew weaker and less purposeful, sinking to its four skeleton knees. When the surrounding people saw that it was safe to approach it, they hacked it to pieces.

Something new had entered human affairs—a thing that could kill at a distance.

It was over in another fifteen minutes—not without more human casualties. The last insect survivor, seeing that it was alone, fled.

“Don’t let it get to its space suit!” Heln cried.

A bunch of people took off in pursuit, but it evaded them. Later, Bram reconstructed what had happened. The insect-thing had killed two people it found in the tunnel on the inner side of the air lock, retrieved its space suit, and charged into the crowd outside. With its coffer of a helmet on—its facial limbs caged up, and, perhaps, its senses muffled—it was no longer aggressive. Nobody outside knew what had been going on. The crowd parted to make way for it, and the deputies were pleased to see that nobody interfered with it. It hightailed it back to its barrel-wheeled vehicle and drove out of town.

The killing spree had left seven dead aliens and more than thirty dead and dismembered human beings. It was going to be hard to tell the enact number until the body parts that were strewn over the chamber were matched up. Bram moved among the weeping people, viewing the butchery. One of the dead was Alb, the junior archivist whom Bram had reprimanded. Somehow he had slipped past the deputies and gotten inside; poor Alb, he had thought it all a lark.

“I suppose it was the space suits,” Heln said, white as flour. “We didn’t look appetizing to them inside ours, and their own feeding impulses were stifled with a sheet of plastic cutting off their sensory world.” She shuddered. “They like their food live and moving. I wonder what kind of livestock they carry with them in that tube vehicle of theirs.”

Nobody had thought about that part of it. Ame looked ill. Bram remembered the creatures’ behavior just before they had taken time out to return to their vehicle for a rest break.

“Maybe animals about the size and shape of a Cuddly,” Bram said. “Possibly even mammals.”

“Yah, the Cuddly popping up in front of that thing was what tripped the switch,” Jao said.

Heln gave the others a bleak look. “Yes, that and poor Jorv, sticking his face inside their unobstructed striking range. Their brains are rewired now. They’ve been programmed to see human beings. As food.”

They spent the next day burying the dead—what could be found of them. Bram found some words in King James that seemed to express what everybody was feeling and read them aloud over his suit radio while the surviving human population stood around the grave site, heads bowed inside their helmets. The terrestrial biology group under Jorv’s assistant took charge of the insect carcasses and began to do autopsies.

When Bram called Yggdrasil, Jun Davd urged him to close down the digs and return at once. “It’s an unlucky place now, I fear. If Heln is correct, the danger’s just beginning.”

“I’m sending the first shuttle loads out today. We should all be evacuated by the day after tomorrow. In the meantime, I’ve posted a guard. The main thing is not to let them get inside the pressurized buildings with us.”

“You ought to know that radio traffic between the colony and the father ship has resumed.”

“They’ve renewed their connection?”

“For the time being. They had something to say to each other. You can imagine what it is.”

“I take your meaning, Jun Davd. I’ll try to speed up the evacuation.”

“It’s hard to abandon what we’ve found of our heritage, I know. But we were going to leave soon, anyway.”

Bitterness clogged Bram’s voice. “Yes, but we always meant to come back one day. Now…”

“Yes,” Jun Davd said somberly. “They’ll have spread to the other disks by then. But Bram, we’ve done wonders in the year we’ve been here—thanks in large part to the spadework the rat archaeologists did for us. We’ve got the great libraries of mankind and a whole biological repository of extinct life forms…”

“I know, Jun Davd. We never thought we’d regain so much of our heritage. Still…” He felt suddenly weary. For the first time, the centuries of wandering seemed to have caught up with him—more than six of them by now, while the clock of the universe had ticked off its tens of millions of years.

“What did Jorv mean, ‘Odonata’?” Bram said.

Jorv’s assistant, Harld, faced him, a scalpel in his hand, still looking pale and shaken. He had a thick white bandage on his head, covering the scalp wound he’d received trying to save a woman from the jaws of an insect-creature, and there were deep scratches down one long bony cheek.

Harld put the scalpel down, looking thoughtful. He paused to look around behind himself where the other two surviving members of the zoology department continued their dissection of one of the insect corpses. The body cavity was laid open, with internal organs spread out fanwise, and Bram did not care for too close a look.

“Odonata? Is that what he said?”

“Yes. Just before he died. He said it after he saw the way the creature grabbed the Cuddly, as if that had made him remember something.”

“It comes from a root in a pre-Inglex language called Greek. It means ‘tooth.’ Original Man used Greek prefixes a lot in scientific classification. Ever since Jorv got back from his trip to the insect camp, he’d been poring over the old archives for insect references, especially from an institution known as the Smithsonian. But there was just so much material to absorb…”

“What does ‘tooth’ have to do with it?”

“It sounds as if it may be the name of the insect order.”

“Can you…”

“There’s nothing to it, now. It’s all alphabetical. Come back in an hour.”

Bram spent the hour arguing with one of the curators from the art team, who wanted to pack an entire shuttle with a collection of paintings and photoplastic art that had been discovered at the last minute.

“It’s irreplaceable,” the man pleaded. “Originals that were on loan from Earth museums. Art that was produced here on the diskworld over a period of several centuries—some of it of the very highest order. We can make a selection—let me assure you that we’re prepared to be very stringent with ourselves—and have it vacuum crated within a Tenday.”

Bram tried to explain that there was neither the space nor the time. “There are still crates of last-minute finds out next to the shuttle pad that are going to have to be abandoned,” he said. “Can’t you make microreproductions of it?”

“You don’t understand!” the curator wailed. “These are originals!”

In the end, it was decided that the curator and his staff would be allowed to take a selection of some of the smaller objects with them as their personal baggage. “The Rembrandt engravings,” the curator decided. “The little votive figurines from the Falwellite thearchy. The photoplastic diskscapes from the neo-literalist period. And some of the small table sculpture. Oh, dear, how will I ever winnow it down?”

Bram suggested that the museum staff load all the excess artwork that they could manage during the next twenty hours on one of the unused rocket-assisted pallets. Some tens of the pallets were slated to be left behind along with a lot of cargo walkers and heavy machinery. “See Jao,” Bram said. “He’ll compute a rough trajectory for you. We’ll have to shoot it off unmanned, but with luck, one of the interbranch vehicles from Yggdrasil will snare it and bring it in.”

“B-but it could be lost forever,” the curator said. “Better to leave it here.”

“No,” Bram said, looking him in the eye. “It wouldn’t.”

That got through. The curator nodded grimly. “I’ll get moving on it right away.”

When Bram returned to Harld, the thin-featured zoologist was waiting for him next to a table spread with photoplastic readouts. He handed one to Bram without comment.

Bram took the stiff sheet from him. It showed a slender, jewellike creature with bulging metallic eyes and four fragile, veined wings.

“Odonata,” Harld said. “Suborder Anisoptera. Also known as the dragonfly, or sometimes by such names as the devil’s darning needle, the mosquito hawk, or the bee butcher.

Bram studied the photograph. He could see several features that suggested a possible provenance for the insect-folk: the domelike eyes, the long segmented body with the claspers at the end, the six wiry legs all grouped together just behind the head.

“Our neighbors across the plain don’t have wings,” he pointed out.

“Neither did their ancestors,” Harld said. “You’re looking at the adult form of the dragonfly. That creature on the dissecting table is descended from an immature form called a nymph.”

Bram looked across at the grisly specimen, the liplike structure with its hooked clasping lobes was spread out to more than a fourth of the creature’s body length. He shuddered.

“Dragonflies spent most of their lives as nymphs,” Harld went on. “Years, sometimes. They lived underwater, breathing through gills, eating voraciously till they grew to size. They’d attack anything that moved—creatures bigger than they were. When it came time for them to change, they’d climb up a reed, split their skin, and emerge as that glorious winged creature you see there. The adult form—the imago—was the one that reproduced. It lived only a few Tendays and died after laying its eggs.”

He handed Bram another photoplastic readout. This one showed a dragonfly climbing out of a pale, cast-off ghost of itself and spreading its gossamer wings.

“What confused the issue,” Harld said, warming to his subject, “was that Odonata’s like no other insect order. There was a separate evolution of the nymphal and imagal forms—probably dating back to before Earth’s Carboniferous period. The dragonfly larva lacked the specialized regeneration centers—’imaginal disks,’ they’re called—that in other insects formed the adult tissues from latent embryonic cells, while the larval tissues melted away. They never went through an intervening pupal stage. They changed by direct growth.”

He was shoving more readouts at Bram. “The nymph adapted for an aquatic life, while the adult dragonfly remained virtually the same,” he said. “The nymph evolved independently. It developed gills. Then, at some point, apparently—like other aquatic creatures—it left the water in its immature form and developed the ability to breathe air.”

Something ugly stirred in Bram’s memory, the shadow of an ancient image.

Harld was trying to show him something on the autopsy table. “Jorv was perfectly right about the way they developed the equivalent of lungs. A portion of the alimentary canal just anterior to the rectum became enlarged into a sort of bellows.”

One of the other zoologists, a freckle-faced fellow, grinned crudely. “What a way to inhale,” he said.

Harld looked annoyed. “It was an obvious evolution-dry step—that’s where the gills were, with their ready-made oxygenating apparatus. In human beings, the embryonic gill structures are derived from the upper alimentary canal—and that’s why breathing and swallowing are interrelated in us.”

The shadowy memory nagged at Bram. There had been something, a long, long time ago…

Harld was saying, “So it was through these aquatic forms that evolution got around the problem of the breathing spiracles that had formerly placed limits on the size and intelligence of land insects. Plus the modification of the exoskeleton into a partially internalized support. It gave the Odonata access to the evolutionary niche previously occupied by the large mammals.”

“And now they’re the inheritors of the earth,” Bram murmured.

Harld frowned. “But first they had to learn how to reproduce in the nymphal stage. Without having to metamorphose into the adult winged form. Because otherwise the need to fly would have placed a limiting factor on their size.”

And then Bram suddenly remembered.

“It was an unstable allele. Original Man spliced a set of synthetic chimeras into dragonfly DNA. They were trying to modify the nymph to create an organism that would keep insect pests under control in their arctic regions. They thought it would remain an aquatic form and do man’s work for him. But it got out of hand.”

“What?” The three zoologists gave their full attention. “Do you know something of this, Bram?”

It all came flooding back. It had been buried for almost seven hundred years in a mind that had become overlaid by other experiences. Slowly at first, then with increasing fluency, Bram told them about the synthetic heterochronic gene that had made the self-reproducing hen’s egg possible—about the way a DNA chimera had been contrived out of genetic material derived from the dragonfly and the axolotl. How, generations later, Original Man had discovered the dangers lurking in the construct and had radioed a warning in a codicil to his first great Message. And how the Nar, accordingly, had suppressed the file—though it contained the seeds of man’s immortality. How he, Bram, a rare human apprentice in a Nar touch group, had stumbled upon the reference and confronted his mentor, Voth, with it. How the entire Nar nation had carried their burden of guilt and finally, stunningly, made amends.

“You’re saying, then, that it was the nymphal dragonflies that exterminated Original Man?” Harld asked.

His eyes were filled with horror. He was wondering, Bram knew, if it was all about to happen again.

“No, no,” Bram said. “Original Man solved the problem. Or thought he had. At great cost. The near destruction of his arctic ecology. But the mutation must just have been biding its time. It waited, buried in dragonfly nucleotides, for forty million years … fifty million years. Long enough for the human race to go the way of the dinosaurs and to be replaced by a dominant species evolved from rats. Long enough for the rat-people to go the way of humankind—according to that timetable of periodic extinctions that your department drew up when we first arrived at the Milky Way. And when the rat-folk were gone, there was an ecological niche vacant, waiting for a new intelligent, cooperating species about the size of a man. No mammal, no vertebrate, could have competed with such as the nymphs had become.”

All of them, the three zoologists and Bram, involuntarily looked over to the dissection table where the latest inheritor of the Earth lay. Harld swallowed hard.

“Man did this?” he asked.

“No, we must not be so arrogant,” Bram said. “Perhaps it would have happened without us.”

Harld opened his mouth as if he were about to say something further. But at that moment Jao came bursting into the improvised morgue.

“Better come quick!” Jao panted. “They’re on their way!”

“Here?”

“Yar. About a hundred of those ground vehicles of theirs. We’ve got to round everybody up and get out to the shuttles before we’re cut off.”

Bram whirled around to the three zoologists. “Get going. Put on your vacuum suits and tell everybody you see to do the same. We’re going to let the air out of this place.”

He turned to Jao again. “All right, let’s start deputizing people. How many of those shuttles are ready to be flown?”

“Enough—if we jam them full of people and dump everything else. In a couple of hours we can strap pallet rockets to some of them. It won’t take much of a boost to at least get them off the ground out of harm’s way. The pilots can finish their countdowns in space if they have to.”

“Good. Let’s get going.”

Jao was sweating. “There’s more,” he said.

“What do you mean?”

“Jun Davd’s been watching the ship through his telescopes. He radioed at almost the exact time our own lookouts saw the ground vehicles starting our way.”

A chill ran down Bram’s spine. “Go on,” he said.

“More of the environmental bubbles are detaching themselves from the stick-ship. They’re just boiling off it. Drifting down to the rim of the diskworld. And some of them are heading toward Yggdrasil.”