However, a ghost is not a real spirit. In the first place, it generally has only a limited power of action; also, it does not have a definite province. It is a vagabond, upon whom no determined task is incumbent, for the effect of death has been to put it outside of all regular forms; as regards the living, it is a sort of a exile. A spirit, on the other hand, always has a power of a certain sort and it is by this that it is defined; it is set over a certain order of cosmic or social phenomena; it has a more or less precise function to fulfil in the system of the universe. But there are some souls which satisfy this double condition and which are consequently spirits, in the proper sense of the word. These are the souls of the mythical personages whom popular imagination has placed at the beginning of time, the Altjirangamitjina or the men of the Alcheringa among the Arunta; the Mura-mura among the tribes of Lake Eyre; the Muk-Kurnai among the Kurnai, etc. In one sense, they are still souls, for they are believed to have formerly animated bodies from which they separated themselves at a certain moment. But even when they led a terrestrial life, they already had, as we have seen, exceptional powers; they had a mana superior to that of ordinary men, and they have kept it. Also, they are charged with definite functions. In the first place, whether we accept the version of Spencer and Gillen or that of Strehlow, it is to them that the care of assuring the periodical recruiting of the clan falls. They have charge of the phenomena of conception. Even when the conception has been accomplished, the task of the ancestor is not yet completed. It is his duty to guard over the new-born child. Later, when the child has become a man, he accompanies him in the hunt, brings game to him, warns him by dreams of the dangers he may run, protects him against his enemies, etc. On this point, Strehlow is entirely in accord with Spencer and Gillen.[870] It is true that someone may ask how it is possible, according to the version of these latter, for the ancestor to fulfil this function; for, since he reincarnates himself at the moment of conception, it seems as though he should be confounded with the soul of the child and should therefore be unable to protect it from without. But the fact is that he does not reincarnate himself entirely; he merely duplicates himself. One part of him enters the body of the woman and fertilizes her; another part continues to exist outside and, under the special name of Arumburinga, fulfils the office of guardian genius.[871]