But while these thinkers have in some cases specifically referred to dreams of the dead, and not merely to the widespread belief of savages that in sleep the soul leaves the body to wander over the earth, they have never realised that there is a special mechanism in the typical dream of a dead friend, due to mental dissociation during sleep, which powerfully suggests to us that death sets up no fatal barrier to the return of the dead. In dreams the dead are thus rendered indestructible; they cannot be finally killed, but rather tend to reappear in ever more clearly affirmed vitality. Dreams of this sort must certainly have come to men ever since men began to be. If their emotional effects are great to-day, we can well believe that they were much greater in the early days when dream life and what we call real life were less easily distinguished. The repercussion of this kind of dream through unmeasured ages cannot fail to have told at last on the traditions of the race. FOOTNOTES: [Footnote 177: I may refer to the very interesting discussion by Professor G. F. Stout (_Analytic Psychology_, vol. ii. p. 145) of the conflict of systems in apperception, and of the suspense and deadlock which occur when two or more systems come into conflict in such a way that the success of one is the defeat of the other. The discussion is full of interest from its undesigned bearing on the phenomena of dreaming.] [Footnote 178: Foucault, for instance (_Le Rêve_, p. 25), discusses and illustrates dreams of this type. I am not here concerned with the causation of this type of dream. Perhaps, as Wundt believes, it is due to some physical discomfort of the sleeper, such as a cramped position, expressing itself symbolically.] [Footnote 179: It may be added that dreams of returning to the school scenes of early life are not necessarily always of the type here described, as may be illustrated by the dream already brought forward on p. 83, which, it is worth while noticing, occurred after a day on which I had been thinking over the dreams of this class.] [Footnote 180: I reproduce these two series in the same form as first published (Havelock Ellis, 'On Dreaming of the Dead,' _Psychological Review_, September 1895) since they have formed the starting point of my own and others' investigation into this type of dream.]