Thales of Miletus is traditionally credited with having been the first philosopher because he was the first to put forward a nonmythological account of the origin and nature of things. However, we know no more of his views than that he claimed that all things originated from water, and it is unlikely that he worked out this thesis in detail. It remained for his “pupil and successor” Anaximander to produce the first comprehensive natural philosophy, a system of astonishing acumen and sophistication.
Anaximander conceived his problem to be that of explaining how the present constitution of the universe developed out of a primordial condition of simplicity. Apparently he did not consider the possibility that things had always been much the same. To this extent, he inherited the notion of evolution from Near Eastern mythologies, which all told of how the world had been fashioned out of a preexisting “chaos” or homogeneous matter, usually water. However, in rejecting divine personal agency and in substituting a (more or less) continuous process for separate acts of creation, Anaximander radically transformed the idea.