were thereupon cast on shore (or perhaps “hatched out”) and took to the land.’ Our knowledge of the πηλαῖοι is limited; but the parallel passage throws some light on Anaximander’s theory. ‘The animals came into existence by a process of evaporation by the sun; but man came into existence in the likeness of another animal, namely, a fish, to begin with.’ Here the theory is, clearly, that there was a stage in the evolution of Man when he ceased to conform to the type even of the highest of marine animals; and it was in the guise of some kind of fish that he took to the land. It is not so clear whether we have here merely the conjecture that at some stage marine vertebrates took the crucial step and invaded the dry land; or whether, also, the similitude of the ‘mud-fish’ is used to report observations which are familiar enough to embryologists now, and in the fifth century were no less familiar to Hippocrates.[71] In any case the views in points of detail which are reported as characteristic of Anaximander presuppose an almost Darwinian outlook on the animal kingdom, and an understanding of comparative anatomy, which hardly becomes possible again before the Renaissance. No less striking is the testimony of the fragment of Archelaus,[72] one of the immediate teachers of Socrates, to the same evolutionary view. ‘Concerning animals he said that when the earth became warm in the beginning in its lower part, where the hot and the cold were mixed, there came to light the rest of the animals, of many dissimilar kinds, but all with the same mode of life, maintained of the slime; and they were short-lived. But, afterwards, interbreeding occurred among these, and men were separated off from the rest, and they constituted leaders and customs and arts and cities and so forth. And, he says, reason is implanted in all animals alike; for each uses it according to his bodily frame, one more tardily, another more promptly.’ Here again we have the biological theory of evolution in a most explicit form, with the same distinction as in Anaximander between the short-lived, infusorian, almost amorphous fauna of sun-warmed water or slime, and the higher orders of thinking vertebrates, among whom Man stands merely as an exceptionally rational species.