Greek philosophy seems to begin with a preposterous fancy, with the proposition that _water_ is the origin and mother-womb of all things. Is it really necessary to stop there and become serious? Yes, and for three reasons: Firstly, because the proposition does enunciate something about the origin of things; secondly, because it does so without figure and fable; thirdly and lastly, because in it is contained, although only in the chrysalis state, the idea: Everything is one. The first mentioned reason leaves Thales still in the company of religious and superstitious people, the second however takes him out of this company and shows him to us as a natural philosopher, but by virtue of the third, Thales becomes the first Greek philosopher. If he had said: "Out of water earth is evolved," we should only have a scientific hypothesis; a false one, though nevertheless difficult to refute. But he went beyond the scientific. In his presentation of this concept of unity through the hypothesis of water, Thales has not surmounted the low level of the physical discernments of his time, but at the best overleapt them. The deficient and unorganised observations of an empiric nature which Thales had made as to the occurrence and transformations of water, or to be more exact, of the Moist, would not in the least have made possible or even suggested such an immense generalisation. That which drove him to this generalisation was a metaphysical dogma, which had its origin in a mystic intuition and which together with the ever renewed endeavours to express it better, we find in all philosophies,--the proposition: _Everything is one!_