Krauss[39] attempted to base the relationship between the dream and insanity upon the etiology (or rather upon the exciting sources), perhaps making the relationship even more intimate than was possible through the analogy of the phenomena they manifest. According to him, the fundamental element common to both is, as we have learned, the organically determined sensation, the sensation of physical stimuli, the general feeling produced by contributions from all the organs. _Cf._ Peise, cited by Maury[48] (p. 60). The incontestable agreement between the dream and mental disturbance, extending into characteristic details, constitutes one of the strongest supports of the medical theory of dream life, according to which the dream is represented as a useless and disturbing process and as the expression of a reduced psychic activity. One cannot expect, however, to derive the final explanation of the dream from the mental disturbances, as it is generally known in what unsatisfactory state our understanding of the origin of the latter remains. It is very probably, however, that a modified conception of the dream must also influence our views in regard to the inner mechanism of mental disturbances, and hence we may say that we are engaged in the elucidation of the psychosis when we endeavour to clear up the mystery of the dream. I shall have to justify myself for not extending my summary of the literature of the dream problems over the period between the first appearance of this book and its second edition. If this justification may not seem very satisfactory to the reader, I was nevertheless influenced by it. The motives which mainly induced me to summarise the treatment of the dream in the literature have been exhausted with the foregoing introduction; to have continued with this work would have cost me extraordinary effort and would have afforded little advantage or knowledge. For the period of nine years referred to has yielded nothing new or valuable either for the conception of the dream in actual material or in points of view. In most of the publications that have since appeared my work has remained unmentioned and unregarded; naturally least attention has been bestowed upon it by the so-called “investigators of dreams,” who have thus afforded a splendid example of the aversion characteristic of scientific men to learning something new. “Les savants ne sont pas curieux,” said the scoffer Anatole France. If there were such a thing in science as right to revenge, I in turn should be justified in ignoring the literature since the appearance of this book. The few accounts that have appeared in scientific journals are so full of folly and misconception that my only possible answer to my critics would be to request them to read this book over again. Perhaps also the request should be that they read it as a whole.