Discipline: Natural Sciences
Thales of Miletus (650.580 B.C.) considered water as the cause of cosmic and organic evolution, whereas Anaximander (610-547 B.C.) believed that living things have arisen from primordial mud. The latter described a kind of succession: plants appeared first, animals next, followed by men who were originally fish-like but left the water to live on land. This conception was changed by Heracleitus (510-450 B.C.) who introduced the idea of conflict among organisms and a struggle for survival.' Opposed to this doctrine was the first evolutionist, Aristotle (384-322 B.C.) who injected into the world the idea of a consistent evolution: the evolution of the egg into the embryo, and the embryo into the perfect state-a concept of development from the lower into the higher forms of being.