oath of the gods. There is an old dogma, he says, that the gods swear by water; but what the gods swear by must be the most ancient, the most sure and steadfast—must be the ground of everything—the very kernel, as we may say, of the universe. Therefore, water must be the ground or kernel of everything. Thales translated into philosophy this old mythological tradition.
6. Here it naturally occurs to one to ask how Thales derived the various objects of the universe from the single principle of water? The only explanation offered is, that these diversified objects are formed by means of a process of thickening or of thinning, which water undergoes. Aristotle's words in reference to this process, although it is somewhat doubtful whether he is speaking of Thales when he uses them, are πυκνότης καὶ μανότης, i.e., a thickening and a thinning, a close consistency and a loose consistency. Water, when its consistency is loose, becomes vapour or air, when its consistency is still looser it becomes a fiery ether; in the same way thickened water becomes slime, and slime, when further condensed, becomes earth. In other words, the rarefaction of the watery principle yields air and fire; the condensation of the watery principle yields slime and earth, and out of the earth all things are produced. Water is thus a very Proteus, which presents itself to us under manifold forms in all the objects we behold. What we call water is only one
