The Rule of Four

Chapter 12

There's an old saw in Frankenstein scholarship that the monster is a metaphor for the novel. Mary Shelley, who was nineteen when she began writing the book, encouraged that interpretation by calling it her hideous progeny, a dead thing with a life of its own. Having lost a child at seventeen, and having caused her own mother's death in childbirth, she must have known what she meant by it.

For a time I thought Mary Shelley was all my thesis subject had in common with Paul's: she and the Roman Francesco Colonna (who was only fourteen, some scholars argued, when the Hypnerotomachia was written) made a pretty couple, two teenagers wise beyond their years. To me, in those months before I met Katie, Mary and Francesco were time-crossed lovers, equally young in different ages. To Paul, standing nose to nose with the scholars of my father's generation, they were an emblem of youth's power against the obstinate momentum of age.

Oddly enough, it was by arguing that Francesco Colonna was an older man, not a younger one, that Paul made his first headway against the Hypnerotomachia. He'd come to Taft freshman year as a bare novice, and the ogre could smell my father's influence on him. Though he claimed to have retired from studying the ancient book, Taft was eager to show Paul the foolishness of my father's theories.

Still favoring the notion of a Venetian Colonna, he explained the strongest piece of evidence in favor of the Pretender.

The Hypnerotomachia was published in 1499, Taft said, when the Roman Colonna was forty-five years old; that much was unproblematic. But the final page of the actual story, which Colonna composed himself, states that the book was written in 1467-when my father's Francesco would only have been fourteen. However unlikely it was that a criminal monk had written the Hypnerotomachia, then, it was outright impossible for a teenager to have done it.

And so, like the curmudgeonly king inventing new labors for young Hercules, Taft left it to Paul to shoulder the burden of proof. Until his new protege could shrug off the problem of Colonna's age, Taft refused to assist any research premised on a Roman author.

It nearly defies explanation, the way Paul refused to buckle under the logic of those facts. He found inspiration not only in Taft's challenge, but in Taft himself: though he rejected the man's rigid interpretation of the Hypnerotomachia, he brought the same relentlessness to his sources. Whereas my father had let inspiration and intuition guide him, searching mainly in exotic locales like monasteries and papal libraries, Paul adopted Taft's more thorough approach. No book was too humble, no location too dull. From top to bottom, he began to scour the Princeton library system. And slowly his early conception of books, like a boy's conception of water who has lived his whole life by a pond, was dethroned by this sudden exposure to the ocean. Paul's book collection, the day he left for college, numbered slightly under six hundred. Princeton's book collection, including more than fifty miles of shelves in Firestone Library alone, numbered well over six million.

The experience daunted Paul at first. The quaint picture my father had painted, of happening across key documents sheerly by accident, was instantly exploded. More painful, I think, was the questioning it forced onto Paul, the introspection and self-doubt that made him wonder if his genius was simply a provincial talent, a dull star in a dark corner of the sky. That upperclassmen in his courses admitted he was far beyond them, and that his professors held him in almost messianic esteem, was nothing to Paul if he couldn't make headway on the Hypnerotomachia.

Then, during his summer in Italy, all that changed. Paul discovered the work of Italian scholars, whose texts he was able to wade through thanks to four years of Latin. Digging into the definitive Italian biography of the Venetian Pretender, he learned that some elements of the Hypnerotomachia were indebted to a book called Cormicoptae, published in 1489. As a detail in the Pretender's life, it seemed unimportant-but Paul, coming at the problem with the Roman Francesco in mind, saw much more in it. No matter when Colonna claimed to have written the book, there was now proof that it was composed after 1489. By then, the Roman Francesco would've been at least thirty-six, not fourteen. And while Paul couldn't imagine why Colonna might lie about the year he wrote the Hypnerotomachia, he realized that he'd answered Taft's challenge. For better or worse, he had entered my father's world.

What followed was a period of soaring confidence. Armed with four languages (the fifth, English, being useless except for secondary sources) and with an extensive knowledge of Colonna's life and times, Paul leapt into the text. He gave more and more of each day to the project, taking a stance toward the Hypnerotomachia that I found uncomfortably familiar: the pages were a battleground where he and Colonna would match wits, winner take all. Vincent Taft's influence, dormant in the months before his trip, had returned. As Paul's interest slowly took the color of obsession, Taft and Stein became increasingly prominent in his life. If it hadn't been for the intervention of one man, I think we might've lost Paul to them entirely.

That man was Francesco Colonna, and his book was hardly the pushover Paul had hoped. Though Paul flexed his mental muscle, he found that the mountain wouldn't move. As his progress slowed, and the fall of junior year darkened into winter, Paul became irritable, quick with sharp comments and rude mannerisms he could only have learned from Taft. At Ivy, Gil told me, members began to joke about Paul when he sat alone at the dinner table, surrounded by stacks of books, talking to no one. The more I watched his confidence dwindle, the more I understood something my father had said once: the Hypnerotomachia is a siren, a fetching song on a distant shore, all claws and clutches in person. You court her at your risk.

And so it went. Spring came; coeds in tank tops tossed Frisbees beneath his window; squirrels and blossoms stooped the tree branches; tennis balls echoed in play; and still Paul sat in his room, alone, shade drawn, door locked, with a message on his whiteboard saying do not disturb. All that I loved about the new season, he called a distraction-the smells and sounds, the sense of impatience after a long and bookish winter. I knew that I myself was becoming a distraction to him. Everything he told me started to sound like the weather report from a foreign land. I visited him little.

It took a summer alone to change him. In early September of senior year, after three months on an empty campus, he welcomed us all back and helped us move in. He was suddenly open to interruptions, eager to spend time among friends, less fixated on the past. In the opening months of that semester, he and I enjoyed a renaissance in our friendship better than anything I could've expected. He shrugged off the onlookers at Ivy who hung on his words, waiting for something outrageous; he spent less time with Taft and Stein; he savored meals and enjoyed walks between classes. He could even see the humor in the way garbage men emptied the Dumpster beneath our window each Tuesday morning at seven o'clock. I thought he was better. More than that: I thought he was reborn.

It was only when Paul came to me in October of senior year, late one night after our last fall midterms, that I understood the other thing our theses had in common: both of our subjects were dead things that refused to stay buried.

Is there anything that could change your mind about working on the Hypnerotomachia?” Paul asked me that night-and from his tense expression, I knew he'd found something important.

No, I told him, half because I meant it, but half to get him to tip his hand.

I think I made a breakthrough over the summer. But I need your help to understand it.

Tell me, I said.

And however it began for my father, whatever galvanized his curiosity in the Hypnerotomachia, this was how it started for me. What Paul said that night gave Colonna's long-dead book new life.

Vincent introduced me to Steven Gelbman from Brown last year when he saw I was getting frustrated, Paul began. Gelbman does research with math, cryptography, and religion, all in one. He's an expert at the mathematical analysis of the Torah. Have you heard of this stuff?

Sounds like kabala.

Exactly. You don't just study what the scriptural words say; you study what the numbers say. Every letter in the Hebrew alphabet has a number assigned to it. Using the order of the letters, you can look for mathematical patterns.

Well, I was doubtful at the beginning. Even after sitting through ten hours of lectures on the Sephirothic correspondences, I didn't buy it. It just didn't seem to relate to Colonna. But by the summer I'd finished the secondary sources on the Hypnerotomachia, and I started working on the book itself. It was impossible. I would try to force an interpretation onto it, and it would throw everything back in my face. As soon as I thought a few pages were moving in one direction, using a certain structure, making a certain point, suddenly the sentence would end, and in the next one everything would change.

I spent five weeks just trying to understand the first labyrinth Francesco describes. I studied Vitruvius to understand the architectural terms. I looked up every ancient labyrinth I knew-the Egyptian one at the City of Crocodiles, the ones at Lemnos and Clusium and Crete, half a dozen others. Then I realized there were four different labyrinths in the Hypnerotomachia—one in a temple, one in the water, one in a garden, and one underground. As soon as I thought I was beginning to understand one level of complexity, it quadrupled. Poliphilo even gets lost at the beginning of the book and says, My only recourse was to beg the pity of Cretan Ariadne, who gave the thread to Theseus to escape from the difficult labyrinth. It's like the book understood what it was doing to me.

Finally I realized the only thing I knew that definitely worked was the acrostic with the first letter of every chapter. So I did what the book told me to do. I begged the pity of Cretan Ariadne, the one person who might be able to solve the maze.

You went back to Gelbman.

He nodded. I ate crow. I was desperate. In July, Gelbman let me stay with him in Providence after Vincent insisted I was making progress with the method. He spent the weekend showing me more sophisticated decoding techniques, and that's when things started to pick up.

I remember looking out the window beyond Paul's shoulder as he spoke, sensing that the landscape was changing. We were sitting in our bedroom in Dod, alone on a Friday night; Charlie and Gil were somewhere below our feet, playing paintball in the steam tunnels with a group of friends from Ivy and the EMT squad. The following day I would have a paper to work on, a test to study for. A week later I would meet Katie for the first time. But for that moment, Paul's hold on my attention was complete.

The most complicated concept he taught me, he continued, was how to decode a book based on algorithms or ciphers from the text itself. In those cases, the key is built right in. You solve for the cipher, like an equation or a set of instructions, then you use the cipher to unlock the text. The book actually interprets itself.

I smiled. Sounds like an idea that could bankrupt the English department.

I was skeptical too, Paul said. But it turns out there's a long tradition of it. Intellectuals during the Enlightenment used to write entire tracts like that as a game. The texts looked like regular stories, epistolary novels, that kind of thing. But if you knew the right techniques-maybe catching typos that turned out to be intentional, or solving puzzles in the illustrations— you could find the key. Something like 'Use only primes and perfect squares, and letters every tenth word shares; exclude the words of Lord Kinkaid, and any questions from the maid.' You would follow the directions, and there would be a message at the end. Most of the time it was a limerick or a dirty joke. But one of these guys actually wrote his will like that. Whoever could decipher it would inherit his estate.

Paul pulled a single sheet of paper from between the pages of a book. On it was written, in two distinct blocks, the text of a passage written in code, and below it the shorter decoded message. How one became the other, I couldn't see.

After a while, I started thinking it could work. Maybe the acrostic with the Hypnerotomachia's chapter letters was just a hint. Maybe it was there to tell you what sort of interpretation would work on the rest of the book. A lot of humanists were interested in kabala, and the idea of playing games with language and symbols was popular in the Renaissance. Maybe Francesco had used some kind of cipher for the Hypnerotomachia.

The problem was, I had no idea where to look for the algorithm. I started inventing ciphers of my own, just to see if one might work. I was fighting with it, day after day. I would come across something, spend a week rummaging through the Rare Books Room for an answer-only to find out it didn't make sense, or it was a trap, or a dead end.

Then, at the end of August, I spent three weeks on a single passage. It's at the point in the story where Poliphilo is examining a set of temple ruins, and he finds a hieroglyphic message carved on an obelisk. To the divine and always august Julius Caesar, governor of the world is the opening phrase. I'll never forget it-it almost drove me crazy. The same few pages, day after day. But that's when I found it.

He opened a binder on his desk. Inside was a reproduction of every page of the Hypnerotomachia. Turning to an appendix he'd created at the end, he showed me a sheet of paper on which he'd clipped the first letter of each chapter into what looked like a ransom note, spelling the famous message about Fra Francesco Colonna. Poliam Frater Franciscus Columna Peramavit.

My starting assumption was simple. The acrostic couldn't just be a parlor trick, a cheap way to identify the author. It had to have a larger purpose: first letters wouldn't just be important for decoding that initial message, they would be important for deciphering the entire book.

So I tried it. The passage I'd been looking at happens to begin with a special hieroglyph in one of the drawings-an eye. He flipped several pages, finally arriving at it.

Since it was the first symbol in that woodcut, I decided it must be important. The problem was, I couldn't do anything with it. Poliphilo's definition of the symbol-that the eye means God, or divinity-led me nowhere.

That's when I got lucky. One morning I was doing some work at the student center, and I hadn't slept much, so I decided to buy a soda. Only, the machine kept spitting my dollar back. I was so tired, I couldn't figure out why, until I finally looked down and realized I was putting it in the wrong way. The back side was up. I was just about to turn it over and try again, when I saw it. Right in front of me, on the back of the bill.

The eye, I said. Right above the pyramid.

Exactly. It's part of the great seal. And that's when it hit me. In the Renaissance there was a famous humanist who used the eye as his symbol. He even printed it on coins and medals.

He waited, as if I might know the answer.

Alberti. Paul pointed to a small volume on the far shelf. The spine read De re aedificatoria. That's what Colonna meant by it. He was about to borrow an idea from Alberti's book, and he wanted you to notice it. If you could just figure out what it was, the rest would fall into place.

In his treatise, Alberti creates Latin equivalents for architectural words derived from Greek. Francesco does the same replacement all over the Hypnerotomachia—except in one place. I'd noticed it the first time I translated the section, because I started hitting Vitruvian terms I hadn't seen in a long time. But I never thought they were significant.

The trick, I realized, was that you had to find all the Greek architectural terms in that passage and replace them with their Latin equivalents, the same way they appear in the rest of the text. If you did that, and used the acrostic rule-reading the first letter of each word in a row, the same way you do with the first letter of each chapter-the puzzle unlocks. You find a message in Latin. The only problem is, if you make just one mistake converting the Greek to Latin, the whole message breaks down. Replace entasi with ventris diametrum instead of just venter, and the extra 'D' at the beginning of diametrum changes everything.

He flipped to another page, talking faster. I made mistakes, of course. Luckily, they weren't so big that I couldn't still piece together the Latin. I took me three weeks, right up to the day before you guys came back to campus. But I finally figured it out. You know what it says? He scratched nervously at something on his face. It says: Who cuckolded Moses?

He gave a hollow laugh. I swear to God, I can hear Francesco laughing at me. I feel like the whole book just boiled down to one big joke at my expense. I mean, seriously. Who cuckolded Moses?

I don't get it.

In other words, who cheated on Moses?

I know what a cuckold is.

Actually, it doesn't literally say cuckold. It says, 'Who gave Moses the horns?' Horns, as early as Artemidorus, are used to suggest cuckoldry. It comes from-

But what does that have to do with the Hypnerotomachia?

I waited for him to explain, or to say that he'd read the riddle wrong. But when Paul got up and started pacing, I could tell this was more complicated.

I don't know. I can't figure out how it fits with the rest of the book. But here's the strange thing. I think I may have solved the riddle.

Someone cuckolded Moses?

Well, sort of. At first, I thought it had to be a mistake. Moses is too major a figure in the Old Testament to be associated with infidelity. As far as I knew, he had a wife-a Midianite woman named Zipporah-but she barely appeared in Exodus, and I couldn't find any reference to her cheating on him.

Then in Numbers 12:1, something unusual happens. Moses' brother and sister speak against him because he marries a Cushite woman. The details are never explained, but some scholars argue that because Cush and Midian are completely different geographical areas, Moses must've had two wives. The name of the Cushite wife never appears in the Bible, but a first-century historian, Flavius Josephus, writes his own account of Moses' life, and claims that the name of the Cushite, or Ethiopian, woman he married was Tharbis.

The details were beginning to overwhelm me. So she cheated on him?

Paul shook his head. No. By taking a second wife, Moses cheated on her, or on Zipporah, whichever one he married first. The chronology is hard to figure out, but in some usages, cuckold's horns appear on the head of the cheater, not just the cheater's spouse. That must be what the riddle's getting at. The answer is Zipporah or Tharbis.

So what do you do with that?

His excitement seemed to dissipate. That's where I've hit a wall. I tried to use Zipporah and Tharbis as solutions every way I could think of, applying them as ciphers to help crack the rest of the book. But nothing works.

He waited, as if expecting me to contribute something.

What does Tart think about it? was all I could think to ask.

Vincent doesn't know. He thinks I'm wasting my time. As soon as he decided Gelbman's techniques weren't yielding breakthroughs, he told me I should go back to following his lead. More focus on the primary Venetian sources.

You're not going to tell him about this?

Paul looked at me as if I misunderstood.

I'm telling you, he said.

I have no idea.

Tom, it can't be an accident. Not something this big. This is what your father was looking for. All we have to do is figure it out. I want your help.

Why?

Now a curious certainty entered his voice, as if he understood something about the Hypnerotomachia that he'd overlooked before. The book rewards different kinds of thought. Sometimes patience works, attention to detail. But other times it takes instinct and inventiveness. I've read some of your conclusions on Frankenstein. They're good. They're original. And you didn't even break a sweat. Just think about it. Think about the riddle. Maybe you'll come up with something else. That's all I'm asking.

There was a simple reason why I rejected Paul's offer that night. In the landscape of my childhood, Colonna's book was a deserted mansion on a hill, a foreboding shadow over any nearby thought. Every unpleasant mystery of my youth seemed to trace its origins to those same unreadable pages: the unaccountable absence of my father from our dinner table so many nights as he labored at his desk; the old arguments he and my mother lapsed into, like saints falling into sin; even the inhospitable oddness of Richard Curry, who fell for Colonna's book worse than any man, and never seemed to recover. I couldn't understand the power the Hypnerotomachia exerted over everyone who read it, but in my experience that power always seemed to play out for the worse. Watching Paul struggle for three years, even if it culminated in this breakthrough, had only helped me keep my distance.

If it seems surprising, then, that I changed my mind the next morning, and joined Paul in his work, chalk it up to a dream I had the night after he told me about the riddle. There is a woodcut in the Hypnerotomachia that will always stay in the stowage of my early childhood, a print that I bumped into many times after sneaking into my father's office to investigate what

he was studying. It's not every day that a boy sees a naked woman reclining under a tree, looking up at him as he returns the favor. And I imagine no one, outside the circle of Hypnerotomachia scholars, can say he has ever seen a naked satyr standing at the feet of such a woman, with a horn of a penis extended like a compass needle in her direction. I was twelve when I saw that picture for the first time, all alone in my father's office, and I could suddenly imagine why he sometimes came to dinner late. Whatever this was, strange and wonderful, beef potluck had nothing on it.

It returned to me that night, the woodcut of my childhood-woman lounging, satyr stalking, member rampant-and I must have done a lot of turning in my bunk, because Paul looked down from his and asked, You okay, Tom?

Coming to, I rose and shot through the books on his desk. That penis, that misplaced horn, reminded me of something. There was a connection to be made. Colonna knew what he was talking about. Someone had given Moses horns.

I found the answer in Hartt's History of Renaissance Art. I'd seen the picture before, but never made anything of it.

What are these? I asked Paul, tossing the book up to his bunk, pointing at the page.

He squinted. Michelangelo's statue of Moses, he said, staring at me as if I'd lost my mind. What's wrong, Tom?

Then, before I even had to explain, he stopped short and turned on his bedside light.

Of course… he whispered, Oh my God, of course.

Sure enough, in the photo I'd shown him, two little nubs stuck out the top of the statue's head, like goatish satyr horns.

Paul jumped down from the bunk, loudly enough that I waited for Gil and Charlie to appear. You did it, he said, eyes wide. This must be it.

He continued like that for a while, until I started to feel an uncomfortable sense of dislocation, wondering how Colonna could've put the answer to his riddle on a Michelangelo sculpture.

So why are they there? I asked finally.

But Paul was already far ahead. He yanked the book off his bunk and showed me the explanation in the text. The horns have nothing to do with being a cuckold. The riddle was literal: who gave Moses horns? It's from a mistranslation of the Bible. When Moses comes down from Mount Sinai, Exodus says, his face glows with rays of light. But the Hebrew word for 'rays' can also be translated as 'horns'-karan versus keren. When Saint Jerome translated the Old Testament into Latin, he thought no one but Christ should glow with rays of light-so he advanced the secondary translation. And that's how Michelangelo carved his Moses. With horns.

In all the excitement, I don't think I even sensed what was happening. The Hypnerotomachia had slunk back into my life, ferrying me across a river I never intended to cross. All that stood in our way was figuring out the significance of Saint Jerome, who had applied the Latin word cornuta to Moses, thus giving him horns. But for the following week, that was a burden Paul happily took upon himself. Beginning that night, and continuing for some time, I was only a hired gun, his last resort against the Hypnerotomachia. I thought it was a position I could keep, a distance I could maintain from the book, letting Paul play the middleman. And so, as he returned to Firestone, white-hot with the possibilities of what we'd found, I went off and made another discovery of my own. Still strutting after my encounter with Francesco Colonna, I can only imagine the impression I made on her.

We met where neither of us belonged, but where both of us felt at home: Ivy. For my part, I'd spent as many weekends there as I had at my own club. For hers, she was already one of Gil's favorites, months before bicker for her sophomore class began, and it was his first thought to introduce us.

Katie, he said, after getting both of us to the club on the same Saturday night, this is my roommate, Tom.

I gave a lazy smile, thinking I didn't have to flex much muscle to charm a sophomore.

Then she spoke. And like a fly in a pitcher plant, expecting nectar and finding death, I realized who was hunting who.

So you're Tom, she said, as if I met the description of a convict from a post office wall. Charlie told me about you.

The best part about being described to someone by Charlie is that things can only get better from there. Apparently he'd met Katie at Ivy several nights earlier, and when he realized that Gil intended to make the match, he eagerly chipped in with details.

What did he tell you? I asked, trying not to look concerned.

She thought for a second, searching for his exact words.

Something about astronomy. About stars.

White dwarf, I told her. It's a science joke.

Katie frowned.

I don't get it either, I admitted, trying to undo my first impression. I'm not much for that kind of stuff.

English major? she asked, as if she could tell.

I nodded. Gil had told me she was into philosophy.

She eyed me suspiciously. Who's your favorite author?

Impossible question. Who's your favorite philosopher?

Camus, she said, even though I meant it rhetorically. And my favorite author is H. A. Rey.

The words came out like a test. I'd never heard of Rey; he sounded like a modernist, a more obscure T.S.Eliot, an uppercase e. e. cummings.

He wrote poetry? I ventured, because I could imagine her reading Frenchmen by firelight.

Katie blinked. Then for the first time since we'd met, she smiled.

He wrote Curious George,'1'' she said, and laughed out loud when I tried not to blush.

That was the recipe of our relationship, I think. We gave each other what we never expected to find. In my earliest days at Princeton I had learned never to talk shop with my girlfriends; even poetry will kill romance, Gil had taught me, if you mistake it for conversation. But Katie had learned the same lesson, and neither of us liked it. Freshman year she dated a lacrosse player I'd met in one of my literature seminars. He was smart, taking to Pynchon and DeLillo in a way I never did, but he refused to speak a word about them outside of class. It drove her crazy, the lines he drew through his life, the walls he put up between work and play. In twenty minutes of conversation that night at Ivy, we both saw something we liked, a willingness to have no walls, or maybe just an unwillingness to keep them standing. It pleased Gil that he'd made such a good match. Before long I found myself waiting for the weekends, hoping to run into her between classes, thinking of her before bed, in the shower, in the middle of tests. Within a month, we were dating.

As the senior in our relationship, I imagined for a while that it was my job to apply the wisdom of my experience to everything we did. I made sure we kept to familiar places and friendly crowds, having learned from past girlfriends that familiarity always arrives in the wake of infatuation: two people who think they're in love can find out, when left alone, exactly how little they know about each other. So I insisted on public places-weekends at eating clubs, weeknights at the student center-and agreed to meet at bedrooms and library nooks only when I thought I detected something more in Katie's voice, the come-hither registers I flattered myself I could hear.

As usual, it was Katie who had to straighten me out.

Come on, she told me one night. We're going to dinner together.

Whose club? I asked.

A restaurant. Your choice.

We'd been together for less than two weeks; there were still too many parts of her I didn't know. A long dinner alone sounded risky.

Did you want to ask Karen or Trish to come along? I asked. Her two roommates in Holder had been fail-safe company. Trish, in particular, who never seemed to eat, dependably talked through any meal.

Katie's back was turned to me. We could ask Gil to come too, she said.

Sure. It struck me as an odd combination, but there was safety in numbers.

What about Charlie? she asked. He's always hungry.

Finally I realized she was being sarcastic.

What's the problem, Tom? she said, turning back to me. You're afraid other people will see us alone?

No.

I bore you?

Of course not.

Then what? You think we'll find out we don't know each other very well?

I hesitated. Yes.

Katie seemed amazed that I meant it.

What's my sister's name? she said finally.

I don't know.

Am I religious?

I'm not sure.

Do I steal money from the tip jar at the coffee shop when I'm short on change?

Probably.

Katie leaned in, smiling. There. You survived.

I'd never been with someone who was so confident about getting to know me. She never seemed to doubt the pieces would fit. Now let's go to dinner, she said, pulling me by the hand. We never looked back.

Eight days after my dream about the satyr, Paul came to me with news. I was right, he said proudly. Parts of the book are written in cipher.

How'd you figure it out?

Cornuta— the word Terome used to give Moses horns-is the answer Francesco wanted. But most of the normal techniques for using a word as a cipher don't work in the Hypnerotomachia. Look…

He showed me a sheet of paper he'd prepared, with two lines of letters running parallel to each other.

Here's a very basic cipher alphabet, he said. The top row is what you call the plaintext, the bottom row is the ciphertext. Notice how the ciphertext begins with our keyword, cornuta? After that, it's just a regular alphabet, with the letters from cornuta removed so they don't get duplicated.

How does it work?

Paul picked up a pencil from his desk and began circling letters. Say you wanted to write 'hello' using this cornuta cipher. You would start with the plaintext alphabet on top and find 'H', then look at its equivalent in ciphertext below it. In this case, 'H' corresponds to 'B.' You do that with the rest of the letters, and 'hello' becomes 'buggj.'

That's how Colonna used cornuta?

No. By the fifteenth and sixteenth centuries, Italian courts had much more sophisticated systems. Alberti, who wrote the architecture treatise I showed you last week, also invented polyalphabetic cryptography. The cipher alphabet changes every few letters. It's much harder.

I point to his sheet of paper. But Colonna couldn't have used anything like that. It just makes gibberish. The whole book would be full of words like 'buggj.'

Paul's eyes lit up. Exactly. Complex encipherment methods don't produce readable text. But the Hypnerotomachia is different. Its ciphertext still reads like a book.

So Colonna used the riddles instead of a cipher.

He nodded. It's called steganography. Like writing a message in invisible ink: the idea is that nobody knows it's there. Francesco combined cryptography and steganography. He hid riddles inside a normal-sounding story, where they wouldn't stand out. Then he used the riddles to create deciphering techniques, to make it harder to understand his message. In this case, all you have to do is count the number of letters in cornuta, which is seven, then string together every seventh letter in the text. It's not that different from using the first word of every chapter. Just a matter of knowing the right intervals.

That worked? Every seventh letter in the book?

Paul shook his head. Not the whole book. Just a part. And no, it didn't work at first. I kept coming up with nonsense. The problem is figuring out where to start. If you choose every seventh letter beginning with the first one, you get a completely different result than if you choose every seventh letter beginning with the second one. That's where the riddle's answer plays a role again.

He pulled another page from his pile, this one a photocopy of an original page from the Hypnerotomachia.

Right here, in the middle of this chapter, is the word cornuta, spelled out in the text of the book itself. If you begin with the *C* in cornuta, and write down every seventh letter for the next three chapters, that's how you find Francesco's plaintext. The original was in Latin, but I translated it. He handed me another sheet. Look.

Good reader, this past year has been the most trying I have endured. Separated from my family, I have had only the good of mankind to comfort me, and while traveling the waters I have seen how flawed that good can be. If it is true, what Pico said, that man is pregnant with all possibilities, that he is a great miracle, as Hermes Trismegistus claimed, then where is the proof? I am surrounded on one side by the greedy and the ignorant, who hope to profit by following me, and on the other side by the jealous and the falsely pious, who hope to profit by my destruction.

But you, reader, are faithful to what I believe, or you could not have found what I have hidden here. You are not among those who destroy in God's name, for my text is their foe, and they are my enemy. I have traveled broadly in search of a vessel for my secret, a way to preserve it against time. A Roman by birth, I was raised in a city built for all ages. The walls and bridges of the emperors stand after a thousand years, and the words of my ancient countrymen have multiplied, reprinted today by Aldus and his colleagues at their presses. Inspired by these creators of the old world, I have chosen the same vessels: a book and a great work of stones. Together they house what I will give to you, reader, if you can understand my meaning.

To learn what I wish to tell, you must know the world as we have known it, -who studied it most of any men in our time. You must prove yourself a lover of wisdom, and of man s potential, so that I will know you are no enemy. For there is an evil abroad, and even we, the princes of our day, do fear it.

Carry on, then, reader. Strive wisely for my meaning. Poliphilo's journey grows harder, as does mine, but I have much more to tell.

I turned the sheet over, looking for more. Where's the rest of it? That's it, he said. We have to solve more to get more. I looked at the page, then up at him in amazement. In the back of my mind, from a corner of unsettled thoughts, came a tapping noise, the sound my father always made when he was excited. His fingers would drum the rhythm of Corelli's Christmas Concerto, twice as fast as any allegro movement, on whatever surface he could find,

What are you going to do now? I asked, trying to stay afloat in the present.

But the thought occurred to me anyway, putting the discovery in perspective: Arcangelo Corelli finished his concerto in the early days of classical music, more than one hundred years before Beethoven's Ninth Symphony. Even in Corelli's day, though, Colonna's message had been awaiting its first reader for more than two centuries.

The same thing you are, Paul said. We're going to find Francesco's next riddle.