570?-500?B.C.

Greek philosopher who thought the source of all things to be infinite and that air was the basic element from which all others came. According to Anaximenes, air, when evenly distributed, is invisible; when condensed, it becomes water; and if further condensed, becomes earth. Fire was regarded as rarefied air. Anaximenes sought the natural causes of phenomena such as rainbows, rather than accepting supernatural explanations. He may have been a student of Anaximander, or at least had read his work.