According to Spencer and Gillen, the souls which, in each generation, come to animate the bodies of newly-born children, are not special and original creations; all these tribes hold that there is a definite stock of souls, whose number cannot be augmented at all,[784] and which reincarnate themselves periodically. When an individual dies, his soul quits the body in which it dwelt, and after the mourning is accomplished, it goes to the land of the souls; but after a certain length of time, it returns to incarnate itself again, and these reincarnations are the cause of conception and birth. At the beginning of things, it was these fundamental souls which animated the first ancestors, the founders of the clan. At an epoch, beyond which the imagination does not go and which is considered the very beginning of time, there were certain beings who were not derived from any others. For this reason, the Arunta call them the _Altjirangamitjina_,[785] the uncreated ones, those who exist from all eternity, and, according to Spencer and Gillen, they give the name _Alcheringa_[786] to the period when these fabulous beings are thought to have lived. Being organized in totemic clans just as the men of to-day are, they passed their time in travels, in the course of which they accomplished all sorts of prodigious actions, the memory of which is preserved in the myths. But a moment arrived when this terrestrial life came to a close; singly or in groups, they entered into the earth. But their souls live for ever; they are immortal. They even continue to frequent the places where the existence of their former hosts came to an end. Moreover, owing to the memories attached to them, these places have a sacred character; it is here that the oknanikilla are located, the sorts of sanctuaries where the churinga of the clan is kept, and the centres of the different totemic cults. When one of the souls which wander about these sanctuaries enters into the body of a woman, the result is a conception and later a birth.[787] So each individual is considered as a new appearance of a determined ancestor: it is this ancestor himself, come back in a new body and with new features. Now, what were these ancestors?