Heraclitus

Heraclitus of Ephesus was a pre-Socratic Greek philosopher born in Ephesus, an Ionian city on the western coast of Asia Minor, today in Turkey and then part of the Persian Empire. He lived around the late sixth and early fifth centuries BC. He is a central figure of ancient Western philosophy because he proposed a view of the world based on constant change and the unity of opposites, ideas that shaped Plato, the Stoics and, centuries later, Hegel, Nietzsche and Heidegger.

Little is known about his life. The main source is Diogenes Laertius, whose accounts are largely unreliable and in many cases appear to be later constructions based on interpretations of the surviving fragments. According to tradition, he was born into an aristocratic family and gave up the hereditary title of king, a largely ceremonial office, passing it to his brother. He is portrayed as a distant and scornful man, critical of the Athenians, of his own fellow citizens and of poets and sages such as Homer, Hesiod, Pythagoras and Xenophanes. He probably withdrew from public life, and he is said to have died painfully of dropsy, though the stories about his death vary and many are legendary.

His only known work was probably titled On Nature, divided according to Diogenes Laertius into three parts: cosmology, politics and theology. The complete text is lost; about a hundred fragments survive through quotations by other authors. His writing is aphoristic, enigmatic and full of paradox, using wordplay, antithesis and oxymoron, which earned him the ancient nickname "the Obscure". Scholars still debate the exact meaning of many of his sentences.

His best-known idea is the permanent flux of things. For him, the world is not made of stable substances but of processes in constant change. His famous saying that one cannot step into the same river twice expresses that, although something seems to stay the same, it keeps changing. This change is not chaotic: the cosmos follows an order, which he called logos, a common principle of reason shared by all things that most people fail to understand. For Heraclitus, opposites are not irreconcilable enemies but tensions that depend on each other: war, night and day, life and death belong to a single unity. He gave fire a special role as the principle of the cosmos, transforming into all things and returning to it, though the interpretation of this idea remains debated. Parmenides, by contrast, held that being is unchanging and that change is an illusion, and that contrast shaped much of the later debate.

His influence has been vast. Plato took up the tension between sensible change and stable knowledge in several dialogues; the Stoics adopted logos as the rational principle of the universe; and in the modern era Hegel saw in him an antecedent of dialectics. Nietzsche admired him as a thinker of becoming and affirmation of life, and Heidegger studied his fragments as an expression of thought predating the split between being and becoming. He is still read today as one of the most suggestive and difficult thinkers of the Greek tradition.