Starting, then, with Thales, we ask why he fixed upon water in his attempt (the earliest recorded) to determine the constitution of the universe? What were the properties, qualities, and functions of that "element" which arrested his attention, and governed his crude, but acute and original, speculations? As already remarked, existing cosmological conceptions played an important rôle, more especially that of the great primeval ocean on which the world was supposed to float. This cosmographical ocean and its accompanying myths will be considered in a subsequent chapter. But restricting our view at present to the physical aspects of water, it is not wholly impossible to recover, and sympathise with, his train of reasoning. Water is wonderfully mobile, incessantly changing, impelled apparently by some inherent principle of movement. Its volatility, also, is very marked; it passes from solid to liquid, and liquid to vapour, and easily reverses the series. More especially would the old-world thinker be struck by the phenomena of the circulation of water. He would see the vapour drawn up by the sun from lake and ocean, seeming to feed the heavenly fires, and returning to earth in the form of rain. He concluded that this must represent the flow of the cosmic process as a whole. Again, in the falling of dew, in the gatherings of mists, and in the welling-up of fountains, the solid materials of the world are apparently passing into a liquid state. Thales was not the first to note these things. They had been subtly modifying the thoughts of men for untold generations. But he was the first whom we know to have gathered together into a definite theory the vague intuitions which had been so long unconsciously operative. He singled out this mobile element and saw in it the substance of the flux of the world as a whole. His theory of movement took a wide range. He did not separate the thing moved from the moving force; nor did he draw any distinction between the organic and inorganic--the mechanical and the vital. He regarded all modes of motion as essentially spontaneous and self-determined. Moreover (as Aristotle tells us) he identified this inherent principle of change with what is divine in nature and in the soul. That is to say, the Real, for Thales, is living impulse and continuous process. It is experienced in man's conscious activities, and constitutes the principle of unity in every mode and form of existence.