* References to the condensation in dreams are to be found in the works of many writers on the subject. Du Prel states in his Philosophie der Mystik that he is absolutely certain that a condensation-process of the succession of ideas had occurred. -

In view of the very great number of ideas which analysis elicits for each individual element of the dream- content, the principal doubt in the minds of many readers will be whether it is permissible to count everything that subsequently occurs to the mind during analysis as forming part of the dream-thoughts- in other words, to assume that all these thoughts have been active in the sleeping state, and have taken part in the formation of the dream. Is it not more probable that new combinations of thoughts are developed in the course of analysis, which did not participate in the formation of the dream? To this objection I can give only a conditional reply. It is true, of course, that separate combinations of thoughts make their first appearance during the analysis; but one can convince oneself every time this happens that such new combinations have been established only between thoughts which have already been connected in other ways in the dream-thoughts; the new combinations are, so to speak, corollaries, short-circuits, which are made possible by the existence of other, more fundamental modes of connection. In respect of the great majority of the groups of thoughts revealed by analysis, we are obliged to admit that they have already been active in the formation of the dream, for if we work through a succession of such thoughts, which at first sight seem to have played no part in the formation of the dream, we suddenly come upon a thought which occurs in the dream-content, and is indispensable to its interpretation, but which is nevertheless inaccessible except through this chain of thoughts. The reader may here turn to the dream of the botanical monograph, which is obviously the result of an astonishing degree of condensation, even though I have not given the complete analysis.

But how, then, are we to imagine the psychic condition of the sleeper which precedes dreaming? Do all the dream-thoughts exist side by side, or do they pursue one another, or are there several simultaneous trains of thought, proceeding from different centres, which subsequently meet? I do not think it is necessary at this point to form a plastic conception of the psychic condition at the time of dream-formation. But let us not forget that we are concerned with unconscious thinking, and that the process may easily be different from that which we observe in ourselves in deliberate contemplation accompanied by consciousness.

The fact, however, is irrefutable that dream-formation is based on a process of condensation. How, then, is this condensation effected?

Now, if we consider that of the dream-thoughts ascertained only the most restricted number are represented in the dream by means of one of their conceptual elements, we might conclude that the condensation is accomplished by means of omission, inasmuch as the dream is not a faithful translation or projection, point by point, of the dream-thoughts, but a very incomplete and defective reproduction of them. This view, as we shall soon perceive, is a very inadequate one. But for the present let us take it as a point of departure, and ask ourselves: If only a few of the elements of the dream-thoughts make their way into the dream- content, what are the conditions that determine their selection?

In order to solve this problem, let us turn our attention to those elements of the dream-content which must have fulfilled the conditions for which we are looking. The most suitable material for this investigation will be a dream to whose formation a particularly intense condensation has contributed. I select the dream, cited in chapter V., of the botanical monograph.