Anaxagoras ("lord of the assembly"; c. 500 BCE – 428 BCE) is a Pre-Socratic Greek philosopher.

Born in Clazomenae in Asia Minor, Anaxagoras is the first philosopher to bring philosophy from Ionia to Athens.

He attempts to give a scientific account of eclipses, meteors, rainbows, and the sun, which he describes as a fiery mass larger than the Peloponnese.

According to Diogenes Laertius and Plutarch he flees to Lampsacus due to a backlash against his pupil Pericles.

Anaxagoras is famous for introducing the cosmological concept of Nous (mind), as an ordering force.

He regards material substance as an infinite multitude of imperishable primary elements, referring all generation and disappearance to mixture and separation respectively.