Archē

Origin or first principle: what the early Greek philosophers sought as the source of all things.

Also: arche, first principle

Greek philosophy and Neoplatonism

Archē means beginning, source and ruling principle. The first philosophers sought the archē of all things: water for Thales, the boundless for Anaximander, air for Anaximenes, fire for Heraclitus. The search marks the beginning of Western philosophy.