Anaxagoras (c.500–428 B.C.), Greek philosopher who was the first of the pre-Socratics to teach in Athens (c.480–450), where he influenced leading intellectuals such as Pericles and Euripides. He left Athens when he was prosecuted for impiety. Writing in response to Parmenides, he elaborated a theory of matter according to which nothing comes into being or perishes. The ultimate realities are stuffs such as water and earth, flesh and bone, but so are contraries such as hot and cold, likewise treated as stuffs. Every phenomenal substance has a portion of every elemental stuff, and there are no minimal parts of anything, but matter takes on the phenomenal properties of whatever predominates in the mixture. Anaxagoras posits an indefinite number of elemental stuffs, in contrast to his contemporary Empedocles, who requires only four elements; but Anaxagoras follows Parmenides more rigorously, allowing no properties or substances to emerge that were not already present in the cosmos as its constituents. Thus there is no ultimate gap between appearance and reality: everything we perceive is real. In Anaxagoras’s cosmogony, an initial chaos of complete mixture gives way to an ordered world when noûs (mind) begins a vortex motion that separates cosmic masses of ether (the bright upper air), air, water, and earth. Mind is finer than the stuffs and is found in living things, but it does not mix with stuffs. Anaxagoras’s theory of mind provides the first hint of a mind–matter dualism. Plato and Aristotle thought his assigning a cosmic role to mind made him sound like ‘a sober man’ among his contemporaries, but they were disappointed that he did not exploit his idea to provide teleological explanations of natural phenomena. See also PRE -SOCRATIC. D.W.G.