Anaxagoras

Life

Anaxagoras was born around 500 BCE in Clazomenae, an Ionian Greek city on the coast of Asia Minor. He reportedly came to Athens around 480 BCE and remained there for approximately thirty years, making him the first major philosopher to be active in the city that would become the center of Greek intellectual life. He became closely associated with Athens' leading statesman, Pericles, and reportedly also knew the tragedian Euripides, whose plays sometimes echo Anaxagorean themes.

Anaxagoras was eventually prosecuted on charges of impiety (asebeia) — specifically, for teaching that the sun is a mass of incandescent stone larger than the Peloponnese and that the moon reflects the sun's light and has plains, mountains, and ravines. These claims, which stripped the heavenly bodies of their divine status, were politically motivated: his enemies attacked him as a proxy for Pericles. He was convicted and exiled (or fled before trial) to Lampsacus on the Hellespont, where he spent his remaining years and was greatly honored after death.

Everything in Everything

Anaxagoras' physical theory was, like Empedocles', a response to Parmenides. But where Empedocles posited four discrete elements, Anaxagoras proposed an infinite number of qualitatively distinct stuffs — what Aristotle later called 'homoiomeries' (things whose parts are like the whole). Gold, flesh, bone, hair, and every other qualitative substance are basic and irreducible. In the original state before cosmic differentiation, all these stuffs were mixed together: "All things were together, infinite in number and in smallness."

The key principle is that 'there is a portion of everything in everything.' Every chunk of matter, no matter how small, contains portions of every kind of stuff. What we call 'gold' is matter in which gold predominates, but it also contains minute portions of flesh, bone, and everything else. This explains how food (which appears to be bread) can nourish flesh, bone, and hair — because the bread already contains portions of flesh, bone, and hair within it. Nothing comes from nothing; apparent coming-to-be is merely the predominance of previously hidden constituents.

Nous (Mind)

Anaxagoras' most celebrated innovation is the introduction of Nous (Mind or Intellect) as a cosmic principle. Nous is radically different from all other things: it is "the finest and purest of all things," it is unlimited (apeiron), self-governing (autokrates), and 'mixed with nothing.' It has complete knowledge of everything and supreme power. Nous initiated the cosmic vortex — the rotational motion that began separating the original mixture into the differentiated world we observe.

Nous controls the rotation, and the rotation mechanically produces the separation of stuffs. Dense, wet, cold, and dark stuffs move toward the center (forming earth); rare, hot, bright stuffs move outward (forming the heavens). The sun is a mass of incandescent stone; the moon is earthy and reflects sunlight; the stars are stones carried by the celestial rotation.

Socrates (as reported by Plato in the Phaedo) expressed great initial excitement about Anaxagoras' Nous, hoping it would provide teleological explanations — explaining why things are arranged for the best. But Socrates was disappointed to find that Anaxagoras used Nous only as a mechanical initiator, a 'deus ex machina' that sets the vortex going and then lets mechanical processes take over. This criticism is a pivotal moment in the history of philosophy, marking the transition from mechanistic to teleological explanation.

Legacy

Anaxagoras died around 428 BCE in Lampsacus. His work, titled 'On Nature,' apparently survived into late antiquity but is now known only through about twenty fragments. His influence was significant: the Atomists partly built on his theory of infinite divisibility, Plato's treatment of Nous in the Phaedo and Timaeus responds to him, and Aristotle's concept of the Unmoved Mover has Anaxagorean roots. His trial for impiety prefigured the trial of Socrates and stands as a landmark in the conflict between free inquiry and religious orthodoxy.