Lives of the Stoics: The Art of Living From Zeno to Marcus Aurelius

In 155 BC, Diogenes of Babylon, the fifth leader of the Stoa, was sent on a diplomatic mission from Athens to Rome. There, he, along with the heads of the other great philosophical schools of Greece, would give a series of lectures about their teachings. This might seem like a minor event, yet it would change not only Rome but the world.

As a form of diplomacy, the idea of sending a group of old philosophers of rival schools to a city notoriously hostile to philosophy seems crazy. Just a few years earlier, the Roman Senate had decreed an outright ban on philosophers, and here Athens went, sending precisely these undesirables to argue and perform on its behalf. It was not sending soldiers. Or professional diplomats. Or lawyers. Or even gifts and bribes. It was sending philosophers. Why?

Desperate times required desperate measures.

The years since Alexander the Great’s death had been an endless series of raids and counterraids in Greece and Italy. The period was marked by the rise and fall of countless kings and principalities. Athens had been under garrison for much of the preceding century and a half as the Macedonian kings fought rivals to hold on to power. Into this breach, Rome slowly gained power, growing from a small city on the Tiber to an international hegemon with colonial ambitions. Supervising a dispute between Athens and a neighbor, Roman-controlled magistrates had decided against Athens and handed down a massive five-hundred-talent fine. It was an amount the city could scarcely afford to pay, so Athens fought back with one of the few weapons it had: its philosophers.

The leader of neither city knew it, but Athens’s decision to dispatch its towering intellectual minds to Rome to appeal the judgment was the first salvo in what would be a century-long battle for cultural supremacy. It was also Stoicism’s first major step out of the classroom and into the halls of power.

So it came to be that Diogenes of Babylon, born the year of Cleanthes’s death, was the first man the Athenians turned to in their hour of need. Hailing from the city of Seleucia in what today is metropolitan Baghdad, Diogenes had studied in Athens under Chrysippus. He was still a young man when Zeno of Tarsus inherited the mantle, and unlike his own more famous predecessor and namesake Diogenes the Cynic, this Diogenes was not some antisocial rebel. He was far too pragmatic for that.

This Diogenes, unlike the famous Diogenes the Cynic, some two centuries before, did not sleep in a barrel. He did not masturbate in public. As far as we know, he wore perfectly reasonable clothes and was capable of civil debate and discussion. He was not a challenger like Aristo or a fighter like Chrysippus. He wasn’t notably funny or clever, but he was a brilliant thinker able to communicate his ideas credibly as a normal functioning citizen of Athens, a respectable leader and not just some clever mind. Diogenes was a rising star in philosophy, making important contributions in the early days of Stoic thinking, including in areas as diverse as linguistics, music, psychology, rhetoric, ethics, and political philosophy.

What brought Diogenes to Stoic philosophy? Plutarch tells us he was inspired by what he’d read of the founder Zeno’s character. It’s a reminder all these years later for everyone considering their legacy. It’s not what you say that lives on after your time; it’s not what you write or even what you build. It’s the example that you set. It’s the things that you live by.

We don’t know when Zeno of Tarsus died and Diogenes succeeded him, but we know that Diogenes was an able teacher who attracted many students. One of them, an abrasive contrarian named Carneades, would go on to lead the skeptical Academy. He had been drawn to Diogenes through the study of the works of Chrysippus, and ended up serving as one of his counterparts in Athens’s diplomatic embassy to Rome.

Again, it says something about the power of philosophy—or at least how far it has fallen since—that these thinkers would be entrusted with such an important mission. But in the ancient world, philosophers occupied a different place than do our professors today.

The diplomatic mission began in a series of public lectures, followed by addresses to the Senate itself, all intended to show off the extreme culture and learning of these heads of the great schools of Athens, thereby softening the sentiment surrounding Rome’s indictment and sentence.

The mission did not begin well. Carneades spoke first, arguing eloquently on the theme of justice to a large, spellbound audience. But the next day he returned, and to a now larger crowd began to argue against justice just as vehemently as he had spoken hours before. One witness, Cato the Elder, one of Rome’s most sober and politically influential citizens, was horrified. What kind of nonsense was this? Where men argue one point and then refute it? He demanded that the brash Carneades be sent home before he could corrupt any more of Rome’s youth.

We don’t know exactly what Diogenes said to the Senate, but it was clearly a calming message, one that presented Athens as a better ally than enemy. Each of the speakers had likely been assigned to talk about the power of justice, to show the Romans that the Greeks were deserving of it. Carneades, in his ego, had threatened to undermine this message, but thankfully Diogenes and Critolaus, the third speaker, were polished and persuasive enough. A gifted and strategic thinker, Diogenes might have argued that harsh punishments would have been less beneficial to Rome than mercy. We are told that the Romans were awed by Diogenes’s “restraint and sobriety,” which was likely heightened by the contrast of his showboating and tone-deaf compatriot.

This was part of Diogenes’s brilliance, and what made him such a great real-world philosopher. Carneades had referred to Rome in one of his speeches as “a city of fools”—not exactly a prudent remark from a man sent to plead for leniency. Worse still, when the insult offended his hosts, he blamed Diogenes, as the Stoics since Zeno believed only a sage was fit to rule. Instead of being abrasive, Diogenes was diplomatic in every sense of the word. He did not rise to provocations or get sucked into conflict.

We can imagine him responding to Carneades’s self-destructive antics and the jeers or criticism of his Roman audience with the same aplomb that he had once dealt with being spit on and heckled by a teenager in Rome. “I’m not angry,” he had replied with a twinkle, “but I’m not sure whether I should be.” So too did he shrug off everything that distracted from this mission from Athens. Too much was at stake.

For all the hoopla about these visiting ambassadors, their learning and eloquence, and the heated arguments over Carneades’s contradictory lectures, this historic political mission was a resounding success. The fine was lowered from five hundred talents to one hundred, and the reputations of the three, especially Diogenes, were established firmly in the Roman mind. Cato the Elder, as appalled as he was by what he witnessed, would unknowingly be proof of the wisdom of the mission. His great-grandson, Cato the Younger (see our subsequent chapter on Rome’s Iron Man), would not only not escape the “corruption” of philosophy, but would become one of the greatest students of Stoicism and win eternal glory through it.

But it was actually Greece and the Stoics themselves who gained the most from this exchange—or rather by the process through which the exchange occurred. Philosophy for the previous several centuries had been primarily a classroom exercise. It had been about the pursuit of the good life—about truth and meaning—but for the student first and foremost. Almost all the philosophical schools—Cynic, Platonist, Aristotelian, Epicurean, even Stoicism—had tuned out the real world of social and political life.

Instead, they argued among themselves about the definition of “virtue.” What need did they have for anything else? Athens may have been the cradle of democracy, but it was like life in a small town. Insular. Sheltered. Self-absorbed. While Zeno had maintained that Stoics must participate in public life unless they are unable—and a few of his students had done so—most, to this point, did not.

The rise of Rome, the call to public service in a crisis like the one that Diogenes had answered, changed that. Cicero, “whose knowledge of previous political philosophy was extensive,” Dirk Obbink writes in his “Diogenes of Babylon: The Stoic Sage in the City of Fools,” “is aware of no Stoic writings concerned with practical political questions before Diogenes.” Sure, there had been some lesser-known Stoics who had served as generals and even died in battle, and others who had advised and consulted with kings, but the teachers of the philosophy had remained largely out of the fray by dealing with politics only in the abstract.

Early Stoic political thought had structured itself largely in opposition to Plato’s Republic and Laws beginning with Zeno’s own quite radical Republic, and continuing in Chrysippus’s work in Against Plato on Justice and in his Exhortations. These debates were little more than arguments about different types of utopia. Before Diogenes of Babylon, Stoic thinking on politics up to this point was best expressed by Chrysippus, who presumably got it from Zeno, that only the sage is truly fit for political leadership.*

It’s an appealing notion, but hardly one that scales. How possible would it be to find enough sages to fill the Senate, let alone to rule an empire? If Carneades is any indication, Athens seemed to have trouble finding enough wise men to fill its embassy to Rome! Exactly why Diogenes would suddenly prioritize a more practical political philosophy makes sense when you understand the shift of power that took place during his lifetime, when the tiny world of Greece fell under the enormous shadow of the rising monolith of Rome.

While it was ultimately successful in the mission to Rome, we know that Athens decided not to pay even the reduced fine that Rome’s magistrates had levied. Was Rome going to go to war over it? Over a fine for Athens’s raid on a neighboring city? After Athens had so masterfully distracted and dazzled the Romans with its philosophy and talk of justice? It was unlikely. And it seems Athens got away with its bluff.

For Diogenes, it must have been an illustrative political moment. While a few centuries later Marcus Aurelius would remind himself that life was not “Plato’s Republic,” Diogenes saw that it wasn’t Zeno’s Republic either. Instead, he saw a world filled with confused and flawed people. Diogenes had seen the truth of this firsthand—and perhaps first of all the Stoics—as he entered Rome and the diplomatic arena. What came from it was a crucial sense of pragmatism that the philosophy desperately needed.

Aristo had seemed to think that philosophy was for the wise man exclusively, for the individual’s self-actualization. His Stoicism worked well in the classroom, and raised interesting debates, but it would not work in the world. Diogenes saw Stoicism differently. It was a way of thinking—as well as a set of rules—for serving the common good, for serving one’s country.

No longer was it sufficient for the philosopher to fantasize about populating a small city exclusively with wise people in order to form the best social order. Nor were the quips and provocations of Diogenes the Cynic—the man who had treated Alexander the Great with disdain—sufficient either. Urgently, the skills of the philosopher—reason, virtue, logic, ethics—were needed outside the Stoa, even outside the agora. To solve problems. To build frameworks and write laws. To guide magistrates. To forge compromises. To persuade and to hold back the passions of the mob. To settle disputes between cities.

Diogenes of Babylon was certainly crafty and had a mind well suited to politics. Cicero tells us about a debate he had with his student Antipater over the ethics of selling a piece of land or a shipment of grain. His student believed that the seller was obligated to fully disclose all information—that several other shipments of grain were coming, likely to drive the price down, or that the asking price for the land was likely higher than its market value. It was only fair and just, he said. But Diogenes argued that nothing would ever sell if every fact was disclosed. How could a market work without the pursuit of mutual self-interest? Besides, sellers have multiple competing obligations, for instance to get the best return for their investors and to provide for their families. Cicero records his direct words of defense: “The seller should declare any defects in his wares, in so far as such a course is prescribed by the common law of the land; but for the rest, since he has goods to sell, he may try to sell them to the best possible advantage, provided he is guilty of no misrepresentation.”

As for everything else, Caveat emptor was his argument. Buyer beware.

“Even if I am not telling you everything,” Diogenes explained, “I am not concealing from you the nature of the gods, or the highest good; yet to know these things would benefit you more than to know that the cheap price of wheat was down.” Is there no better encapsulation of the pragmatic philosophy of this diplomat who had gone to Rome to argue for a reduction of a fine his city likely never intended to pay? Who with one hand dazzled the Romans with speeches while picking their pocket with the other, perhaps telling himself he was preventing Rome from doing the same to Athens? There were competing interests at stake: Athens versus Rome, commercial versus colonial power, paying one’s debts versus fighting an unjust sentence.

Somehow he made it work. He struck a balance of interests and competing loyalties—exactly the role of a diplomat and a political advisor.

He played a similar role settling, in practice, some of the more complicated debates in Stoicism. Aristo had tried to say that we should be indifferent to all things. Diogenes knew that was unrealistic as well. Wealth, he said, was “not merely conducive to achieving pleasure and good health, but essential.” It wasn’t more important than virtue, but it was important—if you could get it. And virtue, according to Cicero’s paraphrasing of his views, “demands life-long steadiness, firmness of purpose and consistency.”

Money made life easier. Virtue, on the other hand, was the work of our life.

Unfortunately, little to none of Diogenes’s writing survives to us, a sad fact given that he was, at least according to the texts that have been discovered entombed in the town destroyed by the eruption of Mount Vesuvius, one of the most cited authors in the ancient world, even more than Plato and Aristotle.

As Diogenes’s works are lost to us, so too was he lost to the world. We not only don’t know how he died, we’re not even sure when. Cicero says that by 150 BC—only a few years after his mission to Rome—Diogenes was dead. Lucian states that he lived to be eighty. But other sources have him living for another decade or until his student Antipater inherited the mantle.

In any case, this prince of philosophy did not live forever, but his legacy—Stoicism as a political force, and the character he exemplified—was only just beginning. In fact, it would soon conquer the world.