Perhaps Cleanthes started when he was younger and “graduated” after nineteen years, before moving on to another role inside the burgeoning school that Zeno was building. In any case, he likely got his start in philosophy at a later age than Zeno (who was only four years his elder).
Kierkegaard would later make the distinction between a genius and an apostle. The genius brings new light and work into the world. The genius is the prophet. The creator. The apostle comes next—a mere man (or woman) who communicates and spreads this message. Given Cleanthes’s dedication to Zeno, it seems likely that the two were never contemporaries or peers, but always master and student. Zeno, the prophet. Cleanthes, the apostle of Stoicism.
Certainly, Cleanthes was the kind of student who warms a teacher’s heart. The one who sits and listens. Who isn’t afraid of asking “dumb” questions. Who puts in the work. Who never gets discouraged, even if they pick things up slower than other students.
Over the course of nearly twenty years, Cleanthes must have sat at the Stoa Poikilē for thousands of hours, not only listening to debates and discussions, but with a front-row seat as the early principles of Stoicism were established. He was there as Zeno divided the curriculum of Stoicism into three parts: physics, ethics, and logic. He would have heard Zeno riff on the choice Heracles made between living a life dedicated to pleasure or one according to virtue, the passage in Xenophon’s Memorabilia that Zeno had first heard in the bookshop and had been so transformed by. Cleanthes, like a sponge, soaked in all of this, believing the whole while that he had much to learn, clearly, for no one with a large ego can remain a student for two decades.
Because of his age, and his methodical, workmanlike approach to things, Cleanthes was sometimes ridiculed as a slow learner and referred to by other students as “the donkey.” When so insulted, he liked to reply that being likened to an ass didn’t bother him because, like the pack animal, he was strong enough to carry the intellectual load Zeno saddled his students with. Zeno, on the other hand, picked a more generous analogy: Cleanthes was like a hard waxen tablet that, being difficult to write upon, nevertheless retains well what’s recorded on it.
Slowly, Cleanthes began to make a name for himself—though it’s impossible to know when he first began writing and publishing for himself.
Some of the first attention he got was not positive. The satirical poet Timon of Phlius parodied him as a simpleton poring over lines of written text like a general reviewing his soldiers:
Who is this, who like a ram ranges over the ranks of warriors? A masticator of words, the stone of Assos, a sluggish slab.
In fact, Assos was famed for its rock quarries and its hard white stone that was used to fashion ancient coffins. When a satirist takes aim at you and finds only your love of language to criticize, it probably says something positive about your character.
So it was for Cleanthes. Quiet. Sober. Hardworking. One with his philosophy. And his money.
Money earned with hard labor is not to be spent frivolously, and Cleanthes did not easily part with his wages or the security they provided. Plutarch marveled at Cleanthes’s frugality and his desire to maintain his financial independence. I continue to carry water, he has Cleanthes say, in order not to be a deserter of Zeno’s instruction, nor from philosophy either. It was said that Cleanthes was supporting his teacher, and that Zeno took a portion of his wages as Athenian law prescribed for masters and their slaves. And even with this payment, Zeno joked that Cleanthes was so disciplined that there was enough left over for him “to maintain a second Cleanthes, if he liked.”
It is clear that Cleanthes abhorred debt and luxury, preferring the freedom of a humble life to the slavery of extravagance. The saying in Athens was that no one was more temperate than Zeno, but Cleanthes did more to establish the Stoic image of indifference to pain or discomfort as well as distaste for luxury. His cloak was once blown open by the cold wind to reveal not even a shirt underneath, a feat of asceticism that passersby spontaneously applauded. Cleanthes was said to be so frugal that he recorded Zeno’s teachings on oyster shells and the blade bones of oxen to save on the cost of papyrus. The latter claim is doubtless an exaggeration, for Diogenes records that Cleanthes wrote fifty books, many in multiple volumes, and we know of another seven from other authors. Though one could speculate that he saved on buying papyrus until he could put it to the best of all possible uses—recording wisdom for the generations.
A young Spartan, raised in a culture of hard living and soldiering, once asked Cleanthes if pain was something to be avoided or whether, with the right training and under the right circumstances, it might be considered a good. This was music to Cleanthes’s ear. Quoting the Odyssey, he responded:
You are of good blood, dear child, because of the kind of words you say.
To Cleanthes, suffering—if in pursuit of virtue—was a good and not an evil. And we can see that in his life. He did not shirk from hardship or discomfort. In fact, he almost seems to have sought them out, to the admiration but also the bafflement of his fellow citizens. What mattered, of course, was where this strength of will was directed. To Cleanthes, we should be striving to become strong in those four virtues Zeno had talked about:
Now this force and strength, when it is in things apparent and to be persisted in, is wisdom; when in things to be endured, it is fortitude; when about worthiness, it is justice; and when about choosing or refusing, it is temperance.
In short: Courage. Justice. Moderation. Wisdom.
Cleanthes, the middle-aged “water-boy,” “the donkey,” the slab of Assos rock, a virtual slave to his master Zeno, would slowly come to acquire a reputation as a kind of new Heracles among his fellow citizens. But as the poet Timon was only the first to illustrate, the fate of any exemplary figure is mockery by parasites, just as the great bull is beset by flies.
With this newfound respect came more criticism as well, particularly as the philosophy became more popular. Zeno and Cleanthes and their students were living differently, thinking differently, holding themselves to vastly different standards not just to the population of Athens but even to their fellow seekers of wisdom. While other schools debated behind closed walls or doors, the Stoics had taken philosophy to the streets. This gave them greater impact and almost made them targets.
Cleanthes dealt with his critics like he dealt with all adversity—as an opportunity to practice what he preached. Once while he sat in a theater, the playwright Sositheus attacked him from the stage by declaiming about those “driven by Cleanthes’ folly like dumb herds.” Cleanthes sat stone-faced, and the audience was so astounded by his calmness that they erupted in applause for his self-discipline and drove the playwright from the stage in response. When Sositheus apologized after the show, Cleanthes readily accepted, saying that greater figures than he had suffered worse abuse by poets and that it would be crazy for him to take offense at such a minor slight.
This came as no surprise to those who knew Cleanthes, as he was a man who held himself to the highest of standards. What some called cowardice or overcautiousness, he better defined as conscientiousness, and believed it was the reason he made so few mistakes. It was not uncommon to find him examining the slightest faults with himself or scolding himself out loud as he walked the streets of Athens. When another of Zeno’s students, Aristo of Chios (see “Aristo the Challenger”), heard him do this, he asked who he was talking to, and Cleanthes laughed, saying, “An old man with grey hair and no wits.”