"It is safest to say," says Professor Burnet, "that it is simply a confused motion this way and that." [Footnote 7] Probably this is a very _safe_ thing to say, because it means nothing in particular. Motion itself cannot be confused. It is only our ideas of motion which can be confused. If this theory is correct, then, we can only say that the Atomists had no definite solution of the problem of the origin of motion and the character of the moving force. They apparently saw no necessity for explanation, which seems unlikely in view of the fact that Empedocles had already seen the necessity of solving the problem, and given a definite, if unsatisfactory, solution, in his theory of Love and Hate. This remark would apply to Democritus, if not to Leucippus. [Footnote 7: _Early Greek Philosophy_, chap. ix. § 179.] The Atomists also spoke of all movement being under the force of "necessity." Anaxagoras was at this time teaching that all motion of things is produced by a world-intelligence, or reason. Democritus expressly opposes to this the doctrine of necessity. There is no reason or intelligence in the world. On the contrary, all phenomena and all becoming are completely determined by blind mechanical causes. In this connection there arises {92} among the Atomists a polemic against the popular gods and the popular religion. Belief in gods Democritus explains as being due to fear of great terrestrial and astronomical phenomena, such as volcanoes, earthquakes, comets, and meteors. But somewhat inconsistently with this, Democritus believed that the air is inhabited by beings resembling men, but larger and of longer life, and explained belief in the gods as being due to projection from these of images of themselves composed of atoms which impinge upon human senses, and produce the ideas of gods.