Works

Thales is said to have predicted the solar eclipse of 585 BCE and to have measured the height of the pyramids by their shadows. These accounts, preserved by Herodotus and others, made him the first figure where science meets philosophy.

Thales wrote nothing that survives. What we know comes from later authors (Aristotle, Diogenes Laertius, and others) who preserved fragments of his thought on water, the soul, and the divine.

The lost prose treatise, possibly the first in the Greek tradition, in which Anaximander set out the boundless as the origin of all things and described a cosmos governed by necessity. Only a single sentence survives, quoted by later writers.

Anaximenes' account of how air, by condensing and thinning, becomes wind, cloud, water, earth, and stone. Surviving only in fragments and later reports, it is the first attempt to explain qualitative change through a single measurable process.

Pythagoras founded a religious community as much as a school. Later sources (Iamblichus, Porphyry, Diogenes Laertius) preserved his teachings on number, music, the transmigration of souls, and the rules of the Pythagorean way of life.

A collection of moral precepts attributed to Pythagoras, though likely composed by later followers. The verses outline a daily practice of self-examination, moderation, and reverence for the cosmic order.

Around forty verse fragments survive from Xenophanes' satires and elegies, preserved as quotations in later authors. In them he mocks the human habit of making gods in our own image, proposes one greatest god unlike mortals in body or thought, and states, earlier than anyone else on record, that certainty about such things is beyond us.

Heraclitus saw the soul as made of fire, the noblest element. A dry, fiery soul is wise; a wet soul is foolish or drunk. These fragments, distinct from his cosmic writings, concern self-knowledge and the depth of inner life.

Fragments from a single work, probably called On Nature. Anaxagoras proposed that Mind (Nous) is the ordering principle of the cosmos, separate from matter and infinite in power.

Zeno's paradoxes survive through Aristotle's reports. They argue that motion, plurality, and space lead to contradiction if you accept the common-sense view of the world.

Two poems, surviving only in fragments. On Nature describes the four roots and the cosmic cycle of Love and Strife. Purifications deals with the transmigration of souls and ritual purity.

Almost nothing survives directly. The two most famous sentences in the history of philosophy are attributed to him, preserved by Plato and Sextus Empiricus.

Gorgias's notorious treatise, surviving only in summary, that runs a chain of arguments to three impossible conclusions: nothing exists; if anything did, it could not be known; and if known, it could not be communicated. Part logic, part provocation, it pushes the limits of reason and language to their breaking point.

One sentence is all that survives in Leucippus' own words, and it states the principle atomism was built on: that nothing is arbitrary. His larger book, The Great World-System, is lost, and ancient readers already disagreed over whether it was his or his student's.

Democritus wrote prolifically (over 70 works by some accounts) but only fragments survive. They reveal a thinker concerned equally with physics and ethics, atoms and cheerfulness.

Democritus was as much a moralist as a physicist. His ethical fragments praise cheerfulness, moderation, and the inner life of the soul over wealth and reputation.

Socrates meets a confident young priest on the courthouse steps and asks him what holiness is. Euthyphro offers five answers and loses each one, and the dialogue ends without a definition — leaving the question that has followed it ever since: is a thing good because the gods love it, or do they love it because it is good?

Socrates goes before dawn to meet the most famous teacher in Greece and asks whether virtue can be taught. Protagoras says it can and tells a myth to prove it; Socrates says it cannot, then argues himself into the opposite position. Both men end holding the view they came to refute.

A dialogue on the nature of love, told through a series of speeches at a drinking party. Socrates recounts the teachings of Diotima on the ascent from physical beauty to the Form of Beauty itself.

Can virtue be taught? Before answering, Socrates calls over an uneducated slave boy and draws squares in the sand until the boy works out a geometrical truth he was never told. From this comes the claim that learning is recollection: the soul already knows, and enquiry is remembering.

A quarrel about rhetoric that turns into a quarrel about how to live. Socrates argues that persuasion without knowledge is flattery, that it is worse to do wrong than to suffer it, and that a man who escapes punishment for injustice is the unluckiest of all. Callicles tells him plainly that philosophy is a game for boys.

Two men walk out of Athens on a hot day and talk about love, and then about speech itself. The soul appears as a charioteer driving two horses, one noble and one unruly. At the end Socrates worries that writing will not strengthen memory but replace it, giving readers the appearance of wisdom without the substance.

What is knowledge? A gifted young mathematician offers three answers — that it is perception, that it is true belief, that it is true belief with an account — and Socrates dismantles all three. He calls himself a midwife who bears no children of his own, and the dialogue ends in honest failure.

A pair of display speeches, the only works of Antisthenes to survive complete out of the ten volumes ancient catalogues credit to him. Each hero argues his own claim to the armor of Achilles: Ajax from deeds, Odysseus from intelligence. The rest of Antisthenes (on nature, on language, on Heracles as the model of philosophical toil) survives only in scattered reports.

Diogenes Laertius preserves a catalogue of Aristippus' books (dialogues, a history of Libya, an essay on education) and then reports, in the same passage, that some authorities claimed he wrote nothing at all. Not one of the titles survives.

Diogenes wrote nothing that survives. His philosophy lives in stories, told by Diogenes Laertius, Plutarch, and others, of radical freedom, public provocation, and devastating wit.

Diogenes reportedly wrote a Republic that made Plato's look tame. It abolished currency, borders, and social convention. Only fragments and descriptions survive through later authors.

A collection of treatises on first philosophy: the study of being as being, substance, causation, and the unmoved mover.

A systematic study of the state, citizenship, and constitutions. Famous for declaring that humans are by nature political animals.

Thirty short sketches of human types (the flatterer, the chatterbox, the penny-pincher, the man of petty ambition), each drawn in a few precise, witty strokes. The first work of character writing, it shaped comedy and the essay for two thousand years.

Zeno's original writings are lost. His teachings survive through students and commentators (Diogenes Laertius, Cicero, Seneca) who preserved the foundations of Stoic philosophy.

Zeno's Republic, written before he fully developed Stoicism, imagined a city governed by the wise, where all citizens live by reason alone. Only fragments survive, but they shaped centuries of political thought.

Pyrrho wrote nothing. His student Timon of Phlius and later Sextus Empiricus preserved his radical teaching: that we should suspend judgment about all things, and in that suspension find peace.

Stories about Pyrrho told by Diogenes Laertius. They paint a man who lived his philosophy: indifferent to danger, unmoved by circumstance, serene in the face of everything.

One of some seven hundred treatises Chrysippus is said to have written, systematizing Stoic propositional logic. Almost nothing survives except through hostile paraphrase in later writers and a handful of scorched fragments recovered from a buried library at Herculaneum.