Anaximander (610 BC – 546 BC)

Anaximander considers reality a variation of the indefinite and limitless unifying element named apeiron. The laws governing both nature and human society stem from this eternal and indestructible entity that makes the ultimate motive force of the universe (somewhat similar to the modern concept of energy). The Greek material monist is the first to conceive a mechanical model of the cosmos (possibly only one of a series of worlds), to use the principle of sufficient reason and to put forth a theory of evolution.