Anaxagoras - ănˌəksăgˈərəs, c.500–428 b.c., Greek philosopher of Clazomenae. He is credited with having transferred the seat of philosophy to Athens. He was closely associated with many famous Athenians and is thought to have been the teacher of Socrates. His belief that the sun was a white-hot stone and that the moon was made of earth that reflected the sun's rays resulted in a charge of atheism and blasphemy, forcing him to flee to Lampsacus, where he died. Rejecting Empedocles' four elements (earth, air, fire, and water), Anaxagoras posits an infinity of particles, or "seeds," each unique in its qualities. All natural objects are composed of particles having all sorts of qualities; a preponderance of similar though not identical particles creates the difference between wood and stone. Anaxagoras' universe, before separation, was an infinite, undifferentiated mass. The formation of the world was due to a rotary motion produced in this mass by an all-pervading mind (nous). This led to the separating out of the "seeds" and the formation of things. Although Anaxagoras was the first to give mind a place in the universe, he was criticized by both Plato and Aristotle for only conceiving of it as a mechanical cause rather than the originator of order.

See D. E. Gershenson and D. A. Greenberg, Anaxagoras and the Birth of Physics (1964); M. Schofield, An Essay on Anaxagoras (1980).

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