It would be interesting to ask the reason. Is it our metaphysical training? Is it the failure of the philosophical schools to realize the value of all this new raw material of study? Is it, perhaps, the fear that “the unity of consciousness” may be endangered by the study of Double Personality, Multiple Personality, Dissociation of Consciousness, Dormant Complexes, Hysterias, Phobias, Obsessions, Psychoneuroses, Fixed Ideas, Hysterical Amnesias, Hypermnesias, and the masses of other notions correlated, roughly, under the term “unconscious”? The suggestion of fear is not mere conjecture. Many years ago a distinguished student of philosophy, a pupil and friend of Sir William Hamilton, indicated to me, when I spoke to him of some recent work on Double Personality, that he had difficulty in placing the new work, feeling that, in admitting the possibility of multiple personality, he was sacrificing the primary concept of philosophy, the unity of consciousness. It did not perhaps occur to him that, when two so-called “persons” speak together, there are, in popular language, “two personalities”—each, no doubt, in a separate body, but each having his own “unity of consciousness.” If this be a fact, is there any greater difficulty in explaining the other fact that two persons may be, as James put it, under the same hat? The metaphysical difficulty, if there be a difficulty, is neither more nor less in the one case than in the other. But it is needless to ask why a whole field of study has been, relatively, neglected in this country. For now we have begun to make up leeway. This translation by Dr. Eder is an introduction to the latest phase of the study of the unconscious. It brings us back to the point I began with, the relation of the normal to the morbid. Dreams are a part of everyone’s normal experience, yet they are shown here to be of the same tissue, of the same mental nature, as other phenomena that are undoubtedly morbid. Dreams therefore offer in the normal a budding-point for the study of morbid growths. And the study of dreams by Freud came long after his studies of such neuroses as the phobias, hysterias, and the rest. To dreams he applied the same method of investigation and treatment as to the others, and he found that dreams offered an unlimited field for the same kind of study.