Greece & Rome · c. 586–526 BCE
Anaximenes
Third Milesian, who made air the first principle
Held that air is the basic stuff: rarefied it becomes fire, condensed it becomes wind, water, earth and stone. This gave a single mechanism, change of density, for how one stuff becomes many.
Life and thought
Anaximenes, the third philosopher of Miletus, is reported to have been Anaximander’s pupil or associate. He worked in the mid-6th century BCE, shortly before the Persians took control of Ionia, and wrote a book in plain prose of which only paraphrases survive.
He chose air as the basic stuff, and his real contribution is how he explained change. Air thinned out becomes fire; thickened, it becomes wind, cloud, water, earth and finally stone. Differences of quality are reduced to differences of quantity, of density. He offered an everyday test: breath blown through pursed lips feels cold, through an open mouth warm. Air also suited the role of a world-soul, since our own soul, he reportedly said, is air that holds us together. Later Ionian thinkers kept his mechanism even when they dropped his choice of stuff.