Fragments

Surviving only as roughly 120 quoted fragments, Heraclitus's writing argues that reality is constant change governed by a single hidden principle he calls the logos, illustrated in aphorisms like the claim that one cannot step into the same river twice. His obscure, riddling style earned him the nickname 'the Obscure' even in antiquity, but his insistence on unity-in-opposition shaped later Stoic and dialectical thought. Heraclitus wrote a single book, now lost, deposited according to tradition in the temple of Artemis at Ephesus, from which later authors, especially Plato, Aristotle, and Diogenes Laertius, preserved the surviving fragments through quotation. Alongside the river image, he illustrated the unity of opposites through the bow and the lyre, instruments that function only through tension between forces pulling in contrary directions.