19. It is incontestable that the soul, in the state of intellectual and moral backwardness that characterizes the peoples that have not emerged from barbarism, cannot possess the same aptitudes for enjoying the splendors of infinity as are possessed by the soul whose intellectual and moral faculties are more largely developed. Therefore, if the souls of barbarians do not progress, those souls can never, throughout eternity, and even while influenced by the most favorable conditions, enjoy anything more than the low and negative happiness of the barbarian degree. The conclusion is consequently forced upon us (if we admit the justice of God), that the souls of the most advanced peoples are the very same souls that were formerly at the barbarian degree of backwardness, but that have since progressed; and we are thus brought face to face with the great question of the plurality of existences, as the only rational solution of the difficulty. We will, however, for the time being, set that solution aside, and consider the soul in a single lifetime.