In his Physics he adopts the Atomic theory of Democritus, though in many respects it ill accords with his Ethics or Canonic; but so low is his esteem of its value that he cares nothing for that. Though atoms and a void are in their nature imperceptible to the senses, he acknowledges their existence, asserting the occurrence of an infinite number of atoms of different kinds in the infinite void, which, because of their weight, precipitate themselves perpendicularly downward with an equable motion; but some of them, through an unaccountable internal force, have deviated from their perpendicular path, and, sticking together after their collision, have given rise to the world. Not much better than these vague puerilities are his notions about the size of the sun, the nature of eclipses, and other astronomical phenomena; but he justifies his contradictions and superficiality by asserting that it is altogether useless for a man to know such things, and that the sage ought to give himself no trouble about them. As to the soul, he says that it must be of a material or corporeal nature, for this simple reason, that there is nothing incorporeal but a vacuum; he inclines to the belief that it is a rarefied body, easily movable, and somewhat of the nature of a vapour; he divides it into four activities, corresponding to the four elements entering into its constitution; and that, so far from being immortal, it is decomposed into its integral atoms, dying when the body dies. With the atomic doctrines of Democritus, Epicurus adopts the notions of that philosopher respecting sensation, to the effect that eidola or images are sloughed off from all external objects, and find access to the brain through the eye. In his theology he admits, under the circumstances we have mentioned, anthropomorphic gods, pretending to account for their origin in the chance concourse of atoms, and suggesting that they display their quietism and blessedness by giving themselves no concern about man or his affairs. By such derisive promptings does Epicurus mock at the religion of his country--its rituals, sacrifices, prayers, and observances. He offers no better evidence of the existence of God than that there is a general belief current among men in support of such a notion; but, when brought to the point, he does not hesitate to utter his disbelief in the national theology, and to declare that, in his judgment, it is blind chance that rules the world. [Sidenote: Epicureans of modern times.]