Flux or movement, says Heraclitus, is the all-pervading law of things, and in the opposition of forces, by which things are kept going, there is underlying harmony. Still on the quest after the primary substance whose manifestations are so various, he found it in FIRE, since "the quantity of it in a flame burning steadily appears to remain the same; the flames seems to be what we call a 'thing.' And yet the substance of it is continually changing. It is always passing away in smoke, and its place is always being taken by fresh matter from the fuel that feeds it. This is just what we want. If we regard the world as an 'ever-living fire'--'this order, which is the same in all things, and which no one of gods or men has made'--we can understand how fire is always becoming all things, while all things are always returning to it." And as is the world, so is man, made up, like it, both soul and body, of the fire, the water, and the earth. We are and are not the same for two consecutive moments; "the fire in us is perpetually becoming water, and the water earth, but as the opposite process goes on simultaneously we appear to remain the same." As speculation advanced, it became more and more applied to details, theories of the beginnings of life being followed by theories of the origin of its various forms. This is a feature of the philosophy of Empedocles, who flourished in the fifth century B. C. The advance of Persia westward had led to migrations of Greeks to the south of Italy and Sicily, and it was at Agrigentum, in that island, that Empedocles was born about 490. He has an honoured place among the earliest who supplanted _guesses_ about the world by _inquiry_ into the world itself. Many legends are told of his magic arts, one of which, it will be remembered, Matthew Arnold makes an occasion of some fine reflections in his poem Empedocles in Etna. The philosopher was said to have brought back to life a woman who apparently had been dead for thirty days. As he ascends the mountain, Pausanias of Gela, with an address to whom the poem of Empedocles opens, would fain have his curiosity slaked as to this and other marvels reported of him: Ask not the latest news of the last miracle, Ask not what days and nights In trance Pantheia lay, But ask how thou such sights May'st see without dismay; Ask what most helps when known, thou son of Anchitus.