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Thinkers

Anaximenes

Ancient Greek · Europe · 586 to 526 BCE

Greek thinker from Miletus who held that air is the basic stuff, and that thickening and thinning of air makes all things.

What it is

Anaximenes was a Greek thinker from Miletus, a city in Ionia. He was the third of the Milesian thinkers, after Thales and Anaximander, and an associate and possibly a pupil of Anaximander. He held that air is the source of all things.

He lived in the middle of the sixth century BCE. The sources differ slightly on his death, giving about 528 or about 526 BCE. What we know of him comes from later writers such as Aristotle and Theophrastus, who reported his views.

The main ideas

  • Air as the source. At one time everything was air, and the other materials of the world came from it.
  • Thin and thick. Air that is thinned becomes fire. Air that is thickened becomes wind, then cloud, then water, then earth, then stones.
  • A test from daily life. Blow on your hand with the mouth relaxed and the breath is warm; blow through pursed lips and it is cold. He took this to show that thin goes with warm and dense with cold.
  • Felting as a comparison. The making of felt, in which wool is compressed, is often compared with the way he thought air changes when it is thinned or packed together.
  • Air and the soul. In early Greek writing air was tied to the soul as the breath of life, and he gave air divine attributes.
  • A flat earth on air. The earth is a flat disc that rides on a cushion of air. The sun circles around it and is hidden at night behind the higher parts of the land. The stars were pictured either as nails fixed in the sky or as leaves floating on air.
  • Weather. Thunder and lightning come from wind breaking out of clouds, rainbows from sunlight meeting clouds, and earthquakes from the ground drying out, being wetted again and cracking.

What it looks like in practice

Imagine someone standing in the cold, breathing out on their hands to warm them, then pursing their lips and feeling the breath turn cool. Anaximenes would say that this small trick is a window onto how the whole world changes, by air being spread thin or packed tight. This is an illustration, not a passage from his writing.

Books and moments

  • Reports by others. Aristotle and Theophrastus are the main writers who preserved what he held.
  • The breath experiment. The simple test with the mouth is reported as his support for the link between thinness and warmth.
  • An early explanation of change. Where Anaximander described a sequence of changes without a clear mechanism, Anaximenes pointed to a process anyone can see.

Questions and criticism

  • One substance or a series? It is fair to ask whether air was for him one underlying substance, with wind, cloud and water only its forms, or whether that reading comes from Aristotle's own, later ideas.
  • Which model for the stars? The reports disagree, giving nails and leaves. It is unclear which, if either, he meant.

Close neighbours

The pages on Thales and Anaximander show the two thinkers before him in Miletus, one choosing water and one an unbounded stuff. Heraclitus and Anaxagoras came after him and were influenced by him.

Written by epchē in our own words, and checked against independent sources on 29 October 2026. The sources are listed below.

Who they connect to

Influenced by

  • Anaximander · He is named as the pupil and successor of Anaximander, and answered his claim that the source is without limit.

Other Ancient Greek thinkers

Sources we used

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