The Interpretation of Dreams. Sigmund Freud

usually present themselves at once to dream-consciousness. It is, so far as the immediate past is concerned, mostly the trifling, the incidental, the "forgotten" impressions of daily life which reappear in our dreams. The psychic activities that are awake most intensely are those that sleep most profoundly."

      Binz⁴ (p. 45) takes occasion from the above-mentioned characteristics of the memory in dreams to express his dissatisfaction with explanations of dreams which he himself has approved of: "And the normal dream raises similar questions. Why do we not always dream of memory impressions from the preceding days, instead of going back to the almost forgotten past lying far behind us without any perceptible reason? Why in a dream does consciousness so often revive the impression of indifferent memory pictures while the cerebral cells bearing the most sensitive records of experience remain for the most part inert and numb, unless an acute revival during the waking state has shortly before excited them?"

      We can readily understand how the strange preference of the dream memory for the indifferent and hence the unnoticed details of daily experience must usually lead us to overlook altogether the dependence of the dream on the waking state, or at least make it difficult to prove this dependence in any individual case. It thus happened that in the statistical treatment of her own and her friend's dreams, Miss Whiton Calkins¹² found 11 per cent. of the entire number that showed no relation to the waking state. Hildebrandt was certainly correct in his assertion that all our dream pictures could be genetically explained if we devoted enough time and material to the tracing of their origin. To be sure, he calls this "a most tedious and thankless job." For it would at most lead us to ferret out all kinds of quite worthless psychic material from the most remote corners of the memory chamber, and to bring to light some very indifferent moments from the remote past which were perhaps buried the next hour after their appearance." I must, however, express my regret that this discerning author refrained from following the road whose beginning looked so unpromising; it would have led him directly to the centre of the dream problem.

      The behaviour of the memory in dreams is surely most significant for every theory of memory in general. It teaches us that "nothing which we have once psychically possessed is ever entirely lost" (Scholz⁵⁹); or as Delbœuf puts it, "que toute impression même la plus insignifiante, laisse une trace inaltérable, indéfiniment susceptible de reparaître au jour," a conclusion to which we are urged by so many of the other pathological manifestations of the psychic life. Let us now bear in mind this extraordinary capability of the memory in the dream, in order to perceive vividly the contradictions which must be advanced in certain dream theories to be mentioned later, when they endeavour to explain the absurdities and incoherence of dreams through a partial forgetting of what we have known during the day.

One might even think of reducing the phenomenon of dreaming to that of memory, and of regarding the dream as the manifestation of an activity of reproduction which does not rest even at night, and which is an end in itself. Views like those expressed by Pilcz⁵¹ would corroborate this, according to which intimate relations are demonstrable between the time of dreaming and the contents of the dream from the fact that the impressions reproduced by the dream in sound sleep belong to the remotest past while those reproduced towards morning are of recent origin. But such a conception is rendered improbable from the outset by the manner of the dream's behaviour towards the material to be remembered. Strümpell⁶⁶ justly calls our attention to the fact that repetitions of experiences do not occur in the dream. To be sure the dream makes an effort in that direction, but the next link is wanting, or appears in changed form, or it is replaced by something entirely novel. The dream shows only fragments of reproduction; this is so often the rule that it admits of theoretical application. Still there are exceptions in which the dream repeats an episode as thoroughly as our memory would in its waking state. Delbœuf tells of one of his university colleagues who in his dream repeated, with all its details, a dangerous wagon ride in which he escaped accident as if by miracle. Miss Calkins¹² mentions two dreams, the contents of which exactly reproduced incidents from the day before, and I shall later take occasion to report an example which came to my notice, showing a childish experience which returned unchanged in a dream.³

       (c) Dream Stimuli and Dream Sources.—What is meant by dream stimuli and dream sources may be explained by referring to the popular saying, "Dreams come from the stomach." This notion conceals a theory which conceives the dream as a result of a disturbance of sleep. We should not have dreamed if some disturbing element had not arisen in sleep, and the dream is the reaction from this disturbance. The discussion of the exciting causes of dreams takes up the most space in the descriptions of the authors. That this problem could appear only after the dream had become an object of biological investigation is self-evident. The ancients who conceived the dream as a divine inspiration had no need of looking for its exciting source; to them the dream resulted from the will of the divine or demoniacal powers, and its content was the product of their knowledge or intention. Science, however, soon raised the question whether the stimulus to the dream is always the same, or whether it might be manifold, and thus led to the question whether the causal explanation of the dream belongs to psychology or rather to physiology. Most authors seem to assume that the causes of the disturbance of sleep, and hence the sources of the dream, might be of various natures, and that physical as well as mental irritations might assume the rôle of dream inciters. Opinions differ greatly in preferring this or that one of the dream sources, in ranking them, and indeed as to their importance for the origin of dreams.

      Wherever the enumeration of dream sources is complete we ultimately find four forms, which are also utilised for the division of dreams:—

      I. External (objective) sensory stimuli.

      II. Internal (subjective) sensory stimuli.

      III. Internal (organic) physical excitations.

      IV. Purely psychical exciting sources.

      I. The External Sensory Stimuli.—The younger Strümpell, son of the philosopher whose writings on the subject have already more than once served us as a guide in the problem of dreams, has, as is well known, reported his observations on a patient who was afflicted with general anaesthesia of the skin and with paralysis of several of the higher sensory organs. This man merged into sleep when his few remaining sensory paths from the outer world were shut off. When we wish to sleep we are wont to strive for a situation resembling the one in Strümpell's experiment. We close the most important sensory paths, the eyes, and we endeavour to keep away from the other senses every stimulus and every change of the stimuli acting upon them. We then fall asleep, although we are never perfectly successful in our preparations. We can neither keep the stimuli away from the sensory organs altogether, nor can we fully extinguish the irritability of the sensory organs. That we may at any time be awakened by stronger stimuli should prove to us "that the mind has remained in constant communication with the material world even during sleep." The sensory stimuli which reach us during sleep may easily become the source of dreams.

      There are a great many stimuli of such nature, ranging from those that are unavoidable, being brought on by the sleeping state or at least occasionally induced by it, to the accidental waking stimuli which are adapted or calculated to put an end to sleep. Thus a strong light may force itself into the eyes, a noise may become perceptible, or some odoriferous matter may irritate the mucous membrane of the nose. In the spontaneous movements of sleep we may lay bare parts of the body and thus expose them to a sensation of cold, or through change of position we may produce sensations of pressure and touch. A fly may bite us, or a slight accident at night may simultaneously attack more than one sense. Observers have called attention to a whole series of dreams in which the stimulus verified on waking, and a part of the dream content corresponded to such a degree that the stimulus could be recognised as the source of the dream.

      I shall here cite a number of such dreams collected by Jessen³⁶ (p. 527), traceable to more or less accidental objective sensory stimuli. "Every indistinctly perceived noise gives rise to corresponding dream pictures; the rolling of thunder takes us into the thick of battle, the crowing of a cock may be transformed into human shrieks of terror, and the creaking of a door may conjure up dreams of burglars breaking into the house. When one of our blankets slips off at night we may dream that we are walking about naked or falling into the water. If we lie diagonally across