Although Plato and his greatest pupil, Aristotle, regarded man’s reasoning soul as spiritual, something distinct from matter, few ancient thinkers were able to rise to the concept of the immateriality of man’s reasoning nature. The Stoics, who in their eclectic system borrowed from both Plato and Aristotle, as well as from many other predecessors, held to a strict materialism which they took from Heraclitus. But to their material principle they applied a concept which they took from Aristotle, for they recognized in all things the existence of an active and a passive principle, and they said that by the action of the former on the latter, all phenomena were produced. The active principle they called reason, intelligence, the cause of all things. It was the world-reason which, according to their view, permeated every part of the cosmos, causing and directing all things. To express their concept of its nature, they often named it Fire, the most powerful and active of the elements, or rather the primordial element; again they often called it God, for they did not hesitate to speak of this immanent principle as a person. Furthermore, since man is a part of the cosmos, the world-reason expresses itself in him. Indeed man’s reason, the directing element of the human soul, is itself a part of the world-reason, or in Epictetus’ striking phrase, man is “a fragment of God.”[14] At this point the Stoic and the Platonist were in accord, although the paths of thought which they had travelled were very different. Yet the Stoic could not agree with the Platonist that the individual soul survived forever, since he held to a cyclical theory of the cosmos, according to which this present universe was temporal. It had been created by the eternal fire, by the world-reason, from itself, and it was destined in due season to sink back again into universal fire. Meantime, according to the views of most Stoics, the souls of the just would survive this body, ascending to the spheres above the world, where they would dwell until absorbed once more into the divine element from which they sprang. To the souls of the wicked only a short period at most of post-corporeal existence was granted--brevity of life or annihilation was their punishment.[15] Strictly speaking, the prospect of the limited existence after death, which the Stoics held out as virtue’s reward, should have had little value for the philosophic mind, especially as their philosophy offered no warrant that personality would survive at all. But it would seem that men at every period of human history have had immortal longings in them so strong that they have eagerly embraced the assurance of even a brief respite from annihilation; certain it is that to many Greeks and Romans the Stoic doctrine of a limited existence after death was a strong incentive to virtue and a consolation in the midst of this world’s trials.