Anaxagoras (an-aks-ag' ō-ras), a Greek philosopher of Clazomenæ, in Ionia, born about 500 B. C. At Athens he had for his pupils Pericles, Thucydides, Euripides and Socrates. He is spoken of as the first theist among philosophers, since he deemed reason the source of truth and matter the creation of an eternal Being, which he called νους (Intelligence). His atomic theory was thought at the time to be a slur on the gods, and for that he was banished, proceeding to Lampsacus, Mysia, where he taught until his death about 428 B. C.