Page:Early Greek philosophy by John Burnet, 3rd edition, 1920.djvu/354

340 doctrine of matter which had been tended by the Ionian physiologists." The detailed cosmology was certainly such a fruit, and it was possibly over-ripe; but the atomic theory proper, in which the real greatness of Leukippos comes out, was wholly Eleatic in its origin. Nevertheless, it will repay us to examine the cosmology too; for such an examination will serve to bring out the true nature of the historical development of which it was the outcome.

178. Leukippos represented the atoms as having been always in motion. Aristotle puts this in his own way. The atomists, he says, "indolently" left it unexplained what was the source of motion, and did not say what sort of motion it was. In other words, they did not decide whether it was a "natural motion" or impressed on them "contrary to their nature." He even said that they made it "spontaneous," a remark which has given rise to the erroneous view that they held it was due to chance. Aristotle does not say that, however; but only that the atomists did not explain the motion of the atoms in any of the ways in which he himself explained the motion of the elements. They neither ascribed to them a natural motion like the circular motion of the heavens and the rectilinear motion of the four elements in the sublunary region, nor did they give them a forced motion contrary to their own nature, like the upward motion that may be given to the heavy elements and the downward that may be given to the light. The only fragment of Leukippos which has survived is an express denial of chance. "Naught happens for nothing," he said, "but everything from a ground and of necessity."