Anaxagoras c. 500 BC – c. 428 BC

Anaxagoras of Clazomenae was an ancient Greek Pre-Socratic philosopher of the 5th century BC, born in Ionia and active for many years in Athens, where he was a friend and reportedly a teacher of Pericles. He held that the cosmos is composed of an infinite number of qualitatively distinct elementary particles, each containing a portion of all things, and that these particles were originally ordered into the perceptible cosmos by a cosmic Mind (nous). The introduction of nous as a principle of cosmic order was widely regarded in antiquity as a major step in the development of Greek philosophy. He was eventually charged in Athens with impiety for his naturalistic explanation of the sun and moon as physical bodies rather than divinities. His writings survive only in fragments.