shall be compelled to advance a number of new assumptions, which do little more than conjecture the structure of the psychic apparatus and the play of the energies active in it; and we shall have to be careful not to go too far beyond the simplest logical construction, since otherwise its value will be doubtful. And even if we should be unerring in our inferences, and take cognizance of all the logical possibilities, we should still be in danger of arriving at a completely mistaken result, owing to the probable incompleteness of the preliminary statement of our elementary data. We shall not he able to arrive at any conclusions as to the structure and function of the psychic instrument from even the most careful investigation of dreams, or of any other isolated activity; or, at all events, we shall not be able to confirm our conclusions. To do this we shall have to collate such phenomena as the comparative study of a whole series of psychic activities proves to be reliably constant. So that the psychological assumptions which we base on the analysis of the dream-processes will have to mark time, as it were, until they can join up with the results of other investigations which, proceeding from another starting-point, will seek to penetrate to the heart of the same problem.

A. The Forgetting of Dreams

What we recollect of the dream, and what we subject to our methods of interpretation, is, in the first place, mutilated by the unfaithfulness of our memory, which seems quite peculiarly incapable of retaining dreams, and which may have omitted precisely the most significant parts of their content. For when we try to consider our dreams attentively, we often have reason to complain that we have dreamed much than we remember; that unfortunately we know nothing more than this one fragment, and that our recollection of even this fragment seems to us strangely uncertain. Moreover, everything goes to prove that our memory reproduces the dream not only incompletely but also untruthfully, in a falsifying manner. As, on the one hand, we may doubt whether what we dreamed was really as disconnected as it is in our recollections, so on the other hand we may doubt whether a dream was really as coherent as our account of it; whether in our attempted reproduction we have not filled in the gaps which really existed, or those which are due to forgetfulness, with new and arbitrarily chosen material; whether we have not embellished the dream, rounded it off and corrected it, so that any conclusion as to its real content becomes impossible. Indeed, one writer (Spitta) * surmises that all that is orderly and coherent is really first put into the dream during the attempt to recall it. Thus we are in danger of being deprived of the very object whose value we have undertaken to determine.

* Similar views are expressed by Foucault and Tannery.

In all our dream-interpretations we have hitherto ignored these warnings. On the contrary, indeed, we have found that the smallest, most insignificant, and most uncertain components of the dream-content invited interpretations no less emphatically than those which were distinctly and certainly contained in the dream. In the dream of Irma's injection we read: "I quickly called in Dr. M," and we assumed that even this small addendum would not have got into the dream if it had not been susceptible of a special derivation. In this way we arrived at the history of that unfortunate patient to whose bedside I quickly called my older colleague. In the seemingly absurd dream which treated the difference between fifty-one and fifty-six as a quantity negligible the number fifty-one was mentioned repeatedly. Instead of regarding this as a matter of course, or a detail of indifferent value, we proceeded from this to a second train of thought in the latent dream-content, which led to the number fifty-one, and by following up this clue we arrived at the fears which proposed fifty-one years as the term of life in the sharpest opposition to a dominant train of thought which was boastfully lavish of the years. In the dream Non vixit I found, as an insignificant interpolation, that I had at first overlooked the sentence: As P does not understand him, Fl asks me, etc. The interpretation then coming to a standstill, I went back to these words, and I found