Anaximander

Anaximander of Miletus was a pupil of Thales who refused to name a familiar element as the first principle, positing instead the apeiron — the boundless, indefinite stuff from which all worlds emerge and to which they return. He drew the first map of the known world and speculated on the origins of life, but his real importance lies in his method: he wrote in prose, argued from evidence, and left the gods out of the story of creation. He is the hinge on which Greek thought turns from myth to philosophy.