Heraclitus
Greek pre-Socratic philosopher (c. 535 – c. 475 BCE), born in Ephesus, in Ionia, into an aristocratic family whose hereditary privileges —including, according to tradition, the city's royal dignity— he renounced in favour of a brother, living apart from public life in explicit contempt for the politics and the masses of his time. Known already in antiquity as 'the Obscure' for his dense, oracular and deliberately cryptic style, he wrote a single book in prose —deposited, according to legend, in the temple of Artemis— of which only around a hundred fragments survive, quoted by later authors such as Plato, Aristotle and Diogenes Laertius, often without context and at times apparently contradictory. His thought revolves around the doctrine of universal flux —'everything flows' (panta rhei), summed up in his most famous image: one cannot step into the same river twice, since both the water and the one who bathes are no longer the same— and, at the same time, a profound unity underlying this constant change, the logos, a universal cosmic reason or law ordering all processes, which most men, lulled by their own private opinion, never manage to perceive despite being constantly immersed in it. He held that reality is a tension of opposites in dynamic balance ('the way up and the way down are one and the same'; 'disease makes health sweet'), that war (polemos) is 'father of all things and king of all things', and that fire is the primordial element from which everything transforms in a measured exchange, as gold is exchanged for goods. His explicit contempt for the crowd, for earlier poets such as Homer and Hesiod, and even for the sage Pythagoras, whom he accused of mere erudition without understanding, earned him a reputation as a misanthrope, but his dynamic conception of reality and his doctrine of the logos deeply influenced Plato, the Stoics —who saw in it an anticipation of their own physics— and, in the modern era, Hegel and Nietzsche.