Anaxagoras (500?–428 B.C.), a Greek philosopher and scientist. He introduced philosophy to Athens. Anaxagoras suggested that mind (nous) is the primary cause of changes in the physical world. He believed that all natural objects are composed of tiny particles, or “seeds,” which contain a mixture of all properties of things and which the mind brings together into an orderly world. As a scientist Anaxagoras was the first to explain eclipses of the sun. He contended the sun is made up of burning rock and that the moon merely reflects light from the sun.

Anaxagoras was born in a Greek colony in Asia Minor, near present-day Izmir (Smyrna), Turkey. He spent most of his adult life as a teacher in Athens. His pupils included Pericles, Euripides, and possibly Socrates. Only fragments of his book. On Nature survive. Anaxagoras was accused of impiety because his theories on the nature of the sun and moon contradicted religious ideas. He was forced to leave Athens and died in Asia Minor.