The Life and Thought of Zeno of Citium in Diogenes Laertius


Joshua J. Mark
published on 11 August 2014

Zeno of Citium (c. 336 – 265 BCE) was the founder of the Stoic School of philosophy in Athens, which taught that the Logos (Universal Reason) was the greatest good in life and living in accordance with reason was the meaning of life. He was born in the Phonecian-Greek city of Citium on Cyprus in the same year that Alexander the Great ascended to the throne of Macedonia. His father was a merchant who traveled often to Athens, and Zeno, naturally, took up his father's profession. It is unclear whether Zeno studied philosophy in his youth but, around the age of 22, while stranded in Athens after a shipwreck, he picked up a copy of Xenophon's Memorabilia and was so impressed by the figure of Socrates that he abandoned his former life and made the study of philosophy his only interest.

Zeno of Citium Bust
Zeno of Citium Bust
Wikipedia User: Rama (CC BY-SA)

It is alleged that Zeno said, “I made a prosperous voyage when I was shipwrecked”, and by this he meant that, prior to his coming to Athens, his life had no meaning. The discipline of philosophy gave Zeno a focus he seems to have lacked as a merchant, and he devoted himself to study and, more importantly, to living the values he absorbed from his teachers and the books he read. Professor Forrest E. Baird writes that Zeno "argued that virtue, not pleasure, was the only good and that natural law, not the random swerving of atoms, was the key principle of the universe" (505). He was praised highly by the Athenians for his temperance, his consistency in living what he taught, and his good effect on the youth of the city. Zeno never seems to have been one to hold his tongue when he saw what he perceived as foolishness in the youths around him, and many of his remarks sound similar in tone to statements Diogenes of Sinope would have made. Unlike the "mad Socrates" of the Agora (as Diogenes was known), Zeno lived a life of traditional Athenian respectability, while refusing to compromise his principles for what society valued.

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Zeno lived and taught in Athens from the time he arrived there following his shipwreck until his death. He died, apparently from suicide, after he tripped coming out of school and broke his toe. Lying on the ground, he quoted a line from the Niobe of Timotheus, “I come of my own accord; why call me thus?” and then, interpreting the accident as a sign he should depart, strangled himself.

The Stoics maintain that the logician is the only wise man.

His life and teachings, like those of other philosophers, were chronicled later by the 3rd century CE writer Diogenes Laertius in his work The Lives and Opinions of Eminent Philosophers. The following selections from Laertius provide a view of the kind of Stoicism Zeno, and his star pupils Cleanthes and Chrisippus, taught. The translation is by C.D. Yonge:

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According to the Stoics, truth follows upon truth, as "It is light," follows upon "It is day." And falsehood follows upon falsehood; as, "If it is false that it is night, it is also false that it is dark." Sometimes too, truth follows from falsehood; for instance, though it is false that "the earth flies," it is true that "there is the earth." But falsehood does never follow from truth; for, from the fact that "there is the earth," it does not follow "that the earth flies."

L. Such then are the doctrines which the Stoics maintain on the subject of logic, in order as far as possible to establish their point that the logician is the only wise man. For they assert that all affairs are looked at by means of that speculation which proceeds by argument, including under this assertion both those that belong to natural aud also those which belong to moral philosophy for, say they, how else could one determine the exact value of nouns, or how else could one explain what laws are imposed upon such and such actions? Moreover, as there are two habits both incidental to virtue, the one considers what each existing thing is, and the other inquires what it is called. These then are the notions of the Stoics on the subject of logic.

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LI. The ethical part of philosophy they divide into the topic of inclination, the topic of good and bad, the topic of the passions, the topic of virtue, the topic of the chief good, and of primary estimation, and of actions; the topic of what things are becoming, and of exhortation and dissuasion. And this division is the one laid down by Chrysippus, and Archedemus, and Zeno, of Tarsus, and Apollodorus, and Diogenes, and Antipater, and Posidonius. For Zeno, of Cittium, and Cleanthes, have, as being more ancient they were likely to, adopted a more simple method of treating these subjects. But these men divided logical and the natural philosophy.

LII. They say that the first inclination which an animal has is to protect itself, as nature brings herself to take an interest in it from the beginning, as Chrysippus affirms in the first book of his treatise on Ends; where he says, that the first and dearest object to every animal is its own existence, and its consciousness of that existence. For that it is not natural for any animal to be alienated from itself, or even to be brought into such a state as to be indifferent to itself, being neither alienated from nor interested in itself. It remains, therefore, that we must assert that nature has bound the animal to itself by the greatest unanimity and affection for by that means it repels all that is injurious, and attracts all that is akin to it and desirable. But as for what some people say, that the first inclination of animals is to pleasure, they say what is false. For they say that pleasure, if there be any such thing at all, is an accessory only, which, nature, having sought it out by itself, as well as these things which are adapted to its constitution, receives incidentally in the same manner as animals are pleased, and plants made to flourish.

Moreover, say they, nature makes no difference between animals and plants, when she regulates them. So as to leave them without voluntary motion or sense; and some things too take place in ourselves in the same manner as in plants. But, as inclination in animals tends chiefly to the point of making them pursue what is appropriate to them, we may say that their inclinations are regulated by nature. And as reason is given to rational animals according to a more perfect principle, it follows, that to live correctly according to reason, is properly predicated of those who live according to nature. For nature is as it were the artist who produces the inclination.

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Zeno of Citium [Pushkin Cast]
Zeno of Citium [Pushkin Cast]
shakko (CC BY-SA)

LIII. On which account Zeno was the first writer who, in his treatise on the Nature of Man, said, that the chief good was confessedly to live according to nature; which is to live according to virtue, for nature leads us to this point. And in like manner Cleanthes speaks in his treatise on Pleasure, and so do Posidonius and Hecaton in their essays on Ends as the Chief Good. And again, to live according to virtue is the same thing as living according to one's experience of those things which happen by nature; as Chrysippus explains it in the first book of his treatise on the Chief Good. For our individual natures are all parts of universal nature; on which account the chief good is to live in a manner corresponding to nature, and that means corresponding to one's own nature and to universal nature; doing none of those things which the common law of mankind is in the habit of forbidding, and that common law is identical with that right reason which pervades everything, being the same with Jupiter, who is the regulator and chief manager of all existing things.

Again, this very thing is the virtue of the happy man and the perfect happiness of life when everything is done according to a harmony with the genius of each individual with reference to the will of the universal governor and manager of all things. Diogenes, accordingly, says expressly that the chief good is to act according to sound reason in our selection of things according to our nature. And Archidemus defines it to be living in the discharge of all becoming duties. Chrysippus again understands that the nature, in a manner corresponding to which we ought to live, is both the common nature, and also human nature in particular; but Cleanthes will not admit of any other nature than the common one alone, as that to which people ought to live in a manner corresponding; and repudiates all mention of a particular nature. And he asserts that virtue is a disposition of the mind always consistent and always harmonious; that one ought to seek it out for its own sake, without being influenced by fear or hope by any external influence. Moreover, that it is in it that happiness consists, as producing in the soul the harmony of a life always consistent with itself; and that if a rational animal goes the wrong way, it is because it allows itself to be misled by the deceitful appearances of exterior things, or perhaps by the instigation of those who surround it; for nature herself never gives us any but good inclinations.

LIV. Now virtue is, to speak generally, a perfection in everything, as in the case of a statue; whether it is invisible as good health, or speculative as prudence. For Hecaton says, in the first book of his treatise on Virtues, that the scientific and speculative virtues are those which have a constitution arising from speculation and study, as, for instance, prudence and justice; and that those which are not speculative are those which are generally viewed in their extension as a practical result or effect of the former; such for instance, as health and strength. Accordingly, temperance is one of the speculative virtues, and it happens that good health usually follows it, and is marshalled as it were beside it; in the same way as strength follows the proper structure of an arch. — And the unspeculative virtues derive their name from the fact of their not proceeding from any acquiescence reflected by intelligence; but they are derived from others, are only accessories, and are found even in worthless people, as in the case of good health, or courage. And Posidonius, in the first hook of his treaties on Ethics, says that the great proof of the reality of virtue is that Socrates, and Diogenes, and Antisthenes, made great improvement; and the great proof of the reality of vice may be found in the fact of its being opposed to virtue.

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Again, Chrysippus, in the first book of his treatise on the Chief Good, and Cleanthes, and also Posidonius in his Exhortations, and Hecaton, all agree that virtue may be taught. And that they are right, and that it may be taught, is plain from men becoming good after having been bad. On this account Panaetius teaches that there are two virtues, one speculative and the other practical; but others make three kinds, the logical, the natural, and the ethical. Posidonius divides virtue into four divisions; and Cleanthes, Chrysippus, and Antipater make the divisions more numerous still; for Apollophanes asserts that there is but one virtue, namely, prudence.

Among the virtues some are primitive [viz., primary] and some are derived. The primitive ones are prudence, manly courage, justice, and temperance. And subordinate to these, as a kind of species contained in them, are magnanimity, continence, endurance, presence of mind, wisdom in council. And the Stoics define prudence as a knowledge of what is good, and bad, and indifferent; justice as a knowledge of what ought to be chosen, what ought to be avoided, and what is indifferent; magnanimity as a knowledge of engendering a lofty habit, superior to all such accidents as happen to all men indifferently, whether they be good or bad; continence they consider a disposition which never abandons right reason, or a habit which never yields to pleasure; endurance they call a knowledge or habit by which we understand what we ought to endure, what we ought not, and what is indifferent; presence of mind they define as a habit which is prompt at finding out what is suitable on a sudden emergency; and wisdom in counsel they think a knowledge which leads us to judge what we are to do, and how we are to do it, in order to act becomingly. And analogously, of vices too there are some which are primary, and some which are subordinate; as, for instance, folly, and cowardice, and injustice, and intemperance, are among the primary vices; incontinence, slowness, and folly in counsel among the subordinate ones. And the vices are ignorance of those things of which the virtues are the knowledge.

LV. Good, looked at in a general way, is some advantage, with the more particular distinction, being partly what is actually useful, partly what is not contrary to utility. On which account virtue itself and the good which partakes of virtue are spoken of in a threefold view of the subject. First, as to what kind of good it is, and from what it ensues; as, for instance, in an action done according to virtue. Secondly, as to the agent, in the case of a good man who partakes of virtue.

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About the Author

Joshua J. Mark
Joshua J. Mark is World History Encyclopedia's co-founder and Content Director. He was previously a professor at Marist College (NY) where he taught history, philosophy, literature, and writing. He has traveled extensively and lived in Greece and Germany.


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Mark, J. J. (2014, August 11). The Life and Thought of Zeno of Citium in Diogenes Laertius. World History Encyclopedia. Retrieved from

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Mark, Joshua J.. "The Life and Thought of Zeno of Citium in Diogenes Laertius." World History Encyclopedia. Last modified August 11, 2014.

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Mark, Joshua J.. "The Life and Thought of Zeno of Citium in Diogenes Laertius." World History Encyclopedia. World History Encyclopedia, 11 Aug 2014. Web. 17 Jun 2024.