Circa 500-Circa 428 B.C.E.
Astronomer And Philosopher

Modern Ideas. Anaxagoras was born in Clazomenae, Anatolia (in present-day Turkey). Around 480 B.C.E. he moved to Athens, where he lived for thirty years and taught a variety of students, including Pericles and possibly Socrates. Unfortunately, few of the writings of Anaxagoras have survived. When he declared that the Sun was an incandescent stone, he was prosecuted for impiety, although the charge was more a political attack on Pericles. He then went into exile and spent his last years at Lampsacus.

Cosmology. Aside from discovering the true cause of eclipses, Anaxagoras made some interesting assertions concerning the physical universe. He declared that natural objects are composed of infinitesimally small particles containing mixtures of all qualities. Accordingly, the nous (mind, reason, or intelligence) acts upon masses of these particles to produce objects. It seemed to him quite impossible that...