Thales of Miletus (640-546 B.C.) was the first cosmologist. Despite the naïvety of his particular theory, that “everything is water”, he was the first to formulate the hypothesis that, in all the multiplicity and diversity of its aspects, the World is One. Although the Babylonians are believed to have conceived the idea of an “Immutable Necessity” dominating all things, as far as we know they had no clear idea of the unity of the universe.