Further, he defended against the Stoics the Peripatetic doctrine of the eternity of the world and the indestructibility of the human race. There is no observed change in the natural order of things; humankind recreates itself in the same manner according to the capacity given by Nature, and the various ills to which it is heir, though fatal to individuals, do not avail to modify the whole. Just as it is absurd to suppose that humans are merely earth-born, so the possibility of their ultimate destruction is inconceivable. The world, as the manifestation of eternal order, must itself be immortal.