- Pupil or younger colleague of Anaximander
- Agreed with Anaximander that arche is infinite, but agreed with Thales that isn’t material instead of indefinite
- Arche candidate is aer (air)
- Change comes through motion of the air (doesn’t need soul for motion)
- Earth is flat and sits on air
- Cloud is thickened moist air, condense to rain
- Earth quake happens when earth is too dry or too wet
- Sun, moon and stars are air refined into fire
- Sun rides around the flat earth and is hidden by mountains at night
- Heat and cold are properties not substances
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