The North American Indians believe in the existence of two souls, one of which remains in the body while the other wanders at pleasure during the dream. The New Zealander supposes that the dreamer's soul leaves his body, and that he meets the things of which he dreams in the course of his wanderings. The Dyak also believes that the soul is absent during sleep, and that the things seen in dreams really occur. Garcilasso asserts that this was likewise the Peruvians' belief. A tribe in Java abstains from waking a sleeper, since his soul is absent in dreams. The Karens say that dreams are what the _la_ or soul sees during sleep. This theory is also found among more civilized peoples, as for instance in the Vedic philosophy and the Kabbala, and it has come down to our days among the common people, and even among those of some culture. One belief connected with dreams, generally diffused among all savage and civilized peoples, is that of the appearance of dead men, or of their ghosts. Of this all the traditions and popular myths in the world are full. Such a belief, first excited by the vision of the dead in dreams, is easily aroused in the savage or uneducated mind, even when he recalls to memory while he is alone, and especially at night, the image of one whom he loved in life. Affection, and the lively emotion of sorrow and desire give such a life-like appearance to these images that they become objectively present to the mind, to console the mourner, or, on the other hand, to threaten the murderer. I have more than once heard persons of all classes, after the death of children, of a husband or wife, whom they have injured or imagine that they have injured, either during life or by not fulfilling their last wishes, declare in all good faith that the form of the dead is often present to their memory and visible while they are awake; thus implying that the dead mercifully appear to comfort their mourning friends, or else to reproach them for not fulfilling their promises. In a word, these images did not seem to them to be subjective, and an ordinary phenomenon of the memory, but objective and personal apparitions within the soul. The cases are not rare in certain dispositions of mind, in which the projection of these images on the memory gradually produces madness. We must not forget that psychical phenomena in general are very differently regarded by the savage and the civilized man, since the latter is accustomed to analysis, and to the real distinctions of things. If this canon is forgotten we shall fall into grave errors in the attempt to interpret the evolution and primitive history of thought and of humanity.