have led, if I mistake not, to light, to explication, and to full understanding, but from the moment that we wish to penetrate deeper into the psychic processes of the dream all paths lead into darkness. It is quite impossible to explain the dream as a psychic process, for to explain means to trace to the known, and as yet we do not possess any psychological knowledge under which we can range what may be inferred from our psychological investigation of dreams as their fundamental explanation. On the contrary, we shall be compelled to build a series of new assumptions concerning the structure of the psychic apparatus and its active forces; and this we shall have to be careful not to carry beyond the simplest logical concatenation, as its value may otherwise merge into uncertainty. And, even if we should make no mistake in our conclusions, and take cognisance of all the logical possibilities involved, we shall still be threatened with complete failure in our solution through the probable incompleteness of our elemental data. It will also be impossible to gain, or at least to establish, an explanation for the construction and workings of the psychic instrument even through a most careful investigation of the dream or any other single activity. On the contrary, it will be necessary for this end to bring together whatever appears decisively as constant after a comparative study of a whole series of psychic activities. Thus the psychological conceptions which we shall gain from an analysis of the dream process will have to wait, as it were, at the junction point until they can be connected with the results of other investigations which may have advanced to the nucleus of the same problem from another starting point.
(a) Forgetting in Dreams.
I propose, then, first, to turn to a subject which has given rise to an objection hitherto unnoticed, threatening to undermine the foundation of our work in dream interpretation. It has been objected in more than one quarter that the dream which we wish to interpret is really unknown to us, or, to be more precise, that we have no assurance of knowing it as it has really occurred (see p. 37). What we recollect of the dream, and what we subject to our methods of interpretation, is in the first place disfigured through our treacherous memory, which
