more than give a name to an inexplicable phenomenon. We call it regression if the presentation in the dream is changed back to the perceptible image from which it once originated. But even this step demands justification. Why this naming, if it does not teach us anything new? I believe, however, that the name "Regression" will serve us to the extent of connecting a fact familiar to us with a scheme of the psychic apparatus which is supplied with a direction. At this point, for the first time, it is worth the trouble to construct such a scheme. For, with the help of this scheme, any other peculiarity of the dream formation will become clear to us without further reflection. If we look upon the dream as a process of regression in the assumed psychic apparatus, we can readily understand the empirically proven fact that all mental relation of the dream thoughts either is lost in the dream-work or can come to expression only with difficulty. According to our scheme, these mental relations are contained not in the first Mem-systems, but in those lying further to the front, and in the regression they must forfeit their expression in favour of the perception pictures. The structure of the dream thoughts is in the regression broken up into its raw material.
But what change renders possible this regression which is impossible during the day? Let us here be content with assumption. There must evidently be some alterations in the charge of energy belonging to the single systems causing the latter to become accessible or inaccessible to the discharge of the excitement; but in any such apparatus the same effect upon the course of excitement might be brought about through more than one form of such changes. This naturally reminds us of the state of sleep and of the many changes of energy this state produces at the sensible end of the apparatus. During the day there is a continuous coursing stream from the Ψ-system of the P toward the motility; this current ceases at night, and no longer hinders a streaming of the current of excitement in the opposite direction. This would appear to be that "seclusion from the outer world" which according to the theory of some authors is supposed to explain the psychological character of the dream (vide p. 30). In the explanation of the regression of the dream we shall, however, have to consider those other regressions which originate during morbid