The descent of the soul from heaven to earth is a fall; the body is a grave in which this soul is buried, a prison in which it is captive. These old Pythagorean doctrines were unceasingly renewed and repeated down to the end of antiquity. But the Orphic idea that this degradation was the chastisement for an original sin, the consequence of a crime committed by the Titans, who were the authors of our race, and that this hereditary taint of guilt had to be atoned for by their descendants, was either entirely forgotten or else, at the least, hardly regarded. The equally ancient conception that a bitter and cruel necessity constrained souls to incarnate themselves, was, on the contrary, emphasised in consequence of the spread of astrological fatalism. Their alternate descent and ascent was conceived as governed by a cosmic law, like the progress and regress of the planets.[442] The cycle of eternal generation (κύκλος γενέσεως) which is eternal, like the revolutions of the heavenly bodies, causes mind to circulate through matter which it animates. This transmigration could be conceived in various ways. A first theory, in which the influence of Stoic pantheism can be recognised, lays stress on the identity of individual souls with the universal soul, of which they are particles. One single divine principle awakens life in all nature. It passes from being to being, quickening their various forms, and that which is said to be death is no more than a migration. The number of the souls that people the earth is determined from the beginning; they change their dwellings but not their essence. Hardly has the human soul left one body before it enters another. This continuous travelling causes it to go through all the degrees of the animal hierarchy. It will pass, successively, into a bird, a quadruped, a fish, a reptile, and then return to man. This is why it is impious to devour the flesh of our “lower brothers” and why the sage must practise vegetarianism. Some thinkers, however, drawing logical conclusions from the admitted premises, asserted that the life of the vegetable kingdom derived from the same migration as that of the animal kingdom and that the soul of man could enclose itself in plants. It was to this teaching that Seneca alluded when he gave the name of _Apocolocyntosis_, “Transformation to a Pumpkin,” to his satire on the apotheosis of the emperor Claudius.