milesian school

The Milesian or Ionian School. Miletus, on the coast of Ionia in Asia Minor, in the 6th century was a prosperous trading center with numerous colonies; its government was aristocratic, and no divinely-backed King or priesthood dominated society and learning.

In order to explain the origin of things and the nature of change and motion, the philosophers in Miletus sought to discover or describe one primary, material substance as the base or elemental foundation of all natural objects and the source of all motion; Thales (early 6th century) postulated that this primary substance was water, Anaximander defined the primary substance as "the unlimited" or "the indefinite" (in Greek: apeiron ), Anaximenes defined it as air.