Heraclitean School of Ancient Greek Philosophy Texts

Roughly one hundred fragments, written in an oracular, aphoristic style, are all that survives of Heraclitus of Ephesus, a Greek thinker active around 500 BCE in Ionia. He founded no school and criticised his predecessors and contemporaries for failing to grasp an underlying unity in things.

His thought centres on the λόγος, an everlasting rational measure that unifies all things and governs a continual process of change. Fire serves as his symbol for the basic material of this process. The doctrine of universal flux — captured in the saying that one cannot step twice into the same river — holds that change is constant but not chaotic: it follows a law-like interchange he called justice, in which opposites such as day and night, or life and death, are necessary to one another and identical within a balanced system of exchanges.

Heraclitus carried this measure into human life. Human laws, he held, are nourished by a single divine law, continuous with the rational measure that governs the cosmos. He distrusted the understanding of the many, believing that few could grasp the λόγος.

He left no institutional school, and his influence travelled through the written fragments and oral transmission, reaching Athens chiefly through his follower Cratylus in the late 5th century BCE, who in turn affected the young Plato. Aristotle read him as a coherent material monist who made fire the ultimate reality, while criticising his doctrines of flux and contradiction. Hellenistic schools, the Stoics among them, adopted his ideas selectively, but no continuous Heraclitean tradition ever existed.