=The Ages have sought for a Unifying Principle.=—We cannot overrate the enormous repose and satisfaction to the human mind contained in the idea of evolution. But it is well to remember that for three thousand years thinkers have been occupied with attempts to explain the world by means of a single principle, which should also furnish an explanation of reason and the human soul. Herakleitos and his age thought they had laid hold of the informing idea in the phrase, ‘The true Being is an eternal Becoming’: the ‘universal flux of things’ explained all. Demokritos and his age cried—Eureka! solved the riddle of the universe, with the saying that ‘nothing exists except atoms moving in vacancy.’ Many times since, with each epoch-making discovery, has science cried—Eureka! over the one principle which should explain all things and eliminate Personality. =But Personality Remains.=—But some little knowledge of history and philosophy will give us pause. We shall see that each great discovery, each luminous idea of nature that the world has received hitherto, is like a bend in a tortuous lake which appears final until your boat approaches it, and then—behold an opening into further and still further reaches beyond! And the knowledge of God will give us something more than the wider outlook which comes of a knowledge of history—the knowledge that there _is_ what Wordsworth calls the ‘stream of tendency,’ a stream of immeasurable force in shaping character and events; but there is also Personality, a power able to turn the ‘stream of tendency’ to its uses, if also liable to be carried away in its current.