which induced me to summarize the treatment of dreams in the literature of the subject have been exhausted by the foregoing introduction; to have continued this would have cost me a great deal of effort and would not have been particularly useful or instructive. For the interval in question- a period of nine years- has yielded nothing new or valuable as regards the conception of dreams, either in actual material or in novel points of view. In most of the literature which has appeared since the publication of my own work the latter has not been mentioned or discussed; it has, of course, received the least attention from the so-called "research-workers on dreams," who have thus afforded a brilliant example of the aversion to learning anything new so characteristic of the scientist. "Les savants ne sont pas curieux," * said the scoffer Anatole France. If there were such a thing in science as the right of revenge, I in my turn should be justified in ignoring the literature which has appeared since the publication of this book. The few reviews which have appeared in the scientific journals are so full of misconceptions and lack of comprehension that my only possible answer to my critics would be a request that they should read this book over again- or perhaps merely that they should read it!

* The learned are not inquisitive.

In the works of those physicians who make use of the psycho-analytic method of treatment a great many dreams have been recorded and interpreted in accordance with my directions. In so far as these works go beyond the confirmation of my own assertions, I have noted their results in the context of my exposition. A supplementary bibliography at the end of this volume comprises the most important of these new publications. The comprehensive work on the dream by Sante de Sanctis, of which a German translation appeared soon after its publication, was produced simultaneously with my own, so that I could not review his results, nor could he comment upon mine. I am sorry to have to express the opinion that this laborious work is exceedingly poor in ideas, so poor that one could never divine from it the possibility of the problems which I have treated in these pages.

I can think of only two publications which touch on my own treatment of the dream-problems. A young philosopher, H. Swoboda, who has ventured to extend W. Fliess's discovery of biological periodicity (in series of twenty-three and twenty-eight days) to the psychic field, has produced an imaginative essay, * in which, among other things, he has used this key to solve the riddle of dreams. Such a solution, however, would be an inadequate estimate of the significance of dreams. The material content of dreams would be explained by the coincidence of all those memories which, on the night of the dream, complete one of these biological periods for the first or the nth time. A personal communication of the author's led me to assume that he himself no longer took this theory very seriously. But it seems that I was mistaken in this conclusion: I shall record in another place some observations made with reference to Swoboda's thesis, which did not, however, yield convincing results. It gave me far greater pleasure to find by chance, in an unexpected quarter, a conception of the dream which is in complete agreement with the essence of my own. The relevant dates preclude the possibility that this conception was influenced by reading my book: I must therefore hail this as the only demonstrable concurrence with the essentials of my theory of dreams to be found in the literature of the subject. The book which contains the passage that I have in mind was published (in its second edition) in 1910, by Lynkeus, under the title Phantasien eines Realisten.

* H. Swoboda, Die Perioden des Menschlichen Organismus, 1904.

ADDENDUM 1914

The above apologia was written in 1909. Since then, the state of affairs has certainly undergone a change; my contribution to the "interpretation of dreams" is no longer ignored in the literature of the subject. But the new situation makes it even more impossible to continue the foregoing summary. The Interpretation of Dreams has evoked a whole series of new contentions and problems, which have been expounded by the authors in the most varied fashions. But I cannot discuss these works until I have developed the theories to which their authors have referred. Whatever has appeared to me as valuable in this recent literature I have accordingly reviewed in the course of the following exposition.