The cosmos as identical with God was described as an individual made up of all being who is incorruptible and ungenerated, the fashioner of the ordered frame of the universe, who at certain periods of time absorbs all being into himself and again generates it from himself. Thus the cosmos on its external side was doomed to perish and the mode of its destruction was to be by fire, a doctrine which has been stamped upon the world's belief down to the present day. What was to bring about this consummation was the soul of the universe becoming too big for its body, which it would eventually swallow up altogether. In the efflagration, when everything went back to the primeval aether, the universe would be pure soul and alive equally through and through. In this subtle and attenuated state, it would require more room than before and so expand into the void, contracting again when another period of cosmic generation had set in. Hence the Stoic definition of the Void or Infinite as that into which the cosmos is resolved at the efflagration. In this theory of the contraction of the universe out of an ethereal state and ultimate return to the same condition one sees a resemblance to the modern scientific hypothesis of the origin of our planetary system out of the solar nebula, and its predestined end in the same. Especially is this the case with the form in which the theory was held by Cleanthes, who pictured the heavenly bodies as hastening to their own destruction by dashing themselves, like so many gigantic moths, into the sun. Cleanthes however did not conceive mere mechanical force to be at work in this matter. The grand apotheosis of suicide which he foresaw was a voluntary act; for the heavenly bodies were Gods and were willing to lose their own in a larger life. Thus all the deities except Zeus were mortal, or at all events, perishable. Gods, like men, were destined to have an end some day. They would melt in the great furnace of being as though they were made of wax or tin. Zeus then would be left alone with his own thoughts, or as the Stoics sometimes put it, Zeus would fall back upon Providence. For by Providence they meant the leading principle or mind of the whole, and by Zeus, as distinguished from Providence, this mind together with the cosmos, which was to it as body. In the efflagration the two would be fused into one in the single substance of aether. And then in the fulness of time there would be a restitution of all things. Everything would come round regularly again exactly as it had been before.