The title which I have given my treatise indicates the tradition which I wish to make the starting-point in my discussion of dreams. I have made it my task to show that dreams are capable of interpretation, and contributions to the solution of the dream problems that have just been treated can only be yielded as possible by-products of the settlement of my own particular problem. With the hypothesis that dreams are interpretable, I at once come into contradiction with the prevailing dream science, in fact with all dream theories except that of Scherner, for to “interpret a dream” means to declare its meaning, to replace it by something which takes its place in the concatenation of our psychic activities as a link of full importance and value. But, as we have learnt, the scientific theories of the dream leave no room for a problem of dream interpretation, for, in the first place, according to these, the dream is no psychic action, but a somatic process which makes itself known to the psychic apparatus by means of signs. The opinion of the masses has always been quite different. It asserts its privilege of proceeding illogically, and although it admits the dream to be incomprehensible and absurd, it cannot summon the resolution to deny the dream all significance. Led by a dim intuition, it seems rather to assume that the dream has a meaning, albeit a hidden one; that it is intended as a substitute for some other thought process, and that it is only a question of revealing this substitute correctly in order to reach the hidden signification of the dream.