Greek cosmologist and pre-Socratic philosopher. He originated the important idea that one substance could account for the diversity of the world (monism). This substance was air or mist. Rarefied, it became fire; condensed, water and earth.
Anaximenes was born in Miletus, Asia Minor. He was the teacher of Anaxagoras. He seems to have chosen air or mist as the basic substance because of its apparent connections with fire, rain, and breath in living creatures.