dream therefore thinks preponderately, but not exclusively, in visual pictures. It also makes use of auditory pictures, and to a lesser extent of the impressions of the other senses. Much is also simply thought or imagined (probably represented by remnants of word presentations), just as in the waking state. But still what is characteristic for the dream is only those elements of the content which act like pictures, i.e. which resemble more the perceptions than the memory presentations. Disregarding all the discussions concerning the nature of hallucinations, familiar to every psychiatrist, we can say, with all well-versed authors, that the dream hallucinates, that is, replaces thoughts through hallucinations. In this respect there is no difference between visual and acoustic presentations ; it has been noticed that the memory of a succession of sounds with which one falls asleep becomes transformed while sinking into sleep into an hallucination of the same melody, so as to make room again on awakening, which may repeatedly alternate with falling into a slumber, for the softer memory presentations which are differently formed in quality.
The transformation of an idea into an hallucination is not the only deviation of the dream from a waking thought which perhaps corresponds to it. From these pictures the dream forms a situation, it presents something in the present, it dramatises an idea, as Spitta64 (p. 145) puts it.8 But the characteristic of this side of the dream life becomes complete only when it is remembered that while dreaming we do not—as a rule; the exceptions require a special explanation—imagine that we are thinking, but that we are living through an experience, i.e., we accept the hallucination with full belief. The criticism that this has not been experienced but only thought in a peculiar manner—dreamt—comes to us only on awakening. This character distinguishes the genuine sleeping dream from day dreaming, which is never confused with reality. The characteristics of the dream life thus far considered have been summed up by Burdach8 (p. 476) in the following sentences: "As characteristic features of the dream we may add (a) that the subjective activity of our mind appears as objective, inasmuch as our faculty of perception perceives the products of phantasy as if they were sensory activities... (b) sleep abrogates one's self-command, hence falling asleep necessitates a certain amount of passivity.... The slumber pictures are conditioned by the relaxation of one's self-command."
It is a question now of attempting to explain the credulity of the mind in reference to the dream hallucinations, which can only appear after the suspension of a certain arbitrary activity. Strümpell66 asserts that the mind behaves in this respect correctly, and in conformity with its mechanism. The dream elements are by no means mere presentations, but true and real experiences of the mind, similar to those that appear in the waking state as a result of the senses (p. 34). Whereas in the waking state the mind represents and thinks in word pictures and language, in the dream it represents and thinks in real tangible pictures (p. 35). Besides, the dream manifests a consciousness of space by transferring the sensations and pictures, just as in the waking state, into an outer space (p. 36). It must therefore be admitted that the mind in the dream is in the same relation to its pictures and perceptions as in the waking state (p. 43). If, however, it is thereby led astray, this is due to the fact that it lacks in sleep the criticism which alone can distinguish between the sensory perceptions emanating from within or from without. It cannot subject its pictures to the tests which alone can prove their objective reality. It furthermore neglects to differentiate between pictures that are arbitrarily interchanged and others where there is no free choice. It errs because it cannot apply to its content the law of causality (p. 58). In brief, its alienation from the outer world contains also the reason for its belief in the subjective dream world.
Delbœuf16 reaches the same conclusion through a somewhat different line of argument. We give to the dream pictures the credence of reality because in sleep we have no other impressions to compare them with, because we are cut off from the outer world. But it is not perhaps because we are unable to make tests in our sleep, that we believe in the truth of our hallucinations. The dream may delude us with all these tests, it may make us believe that we may touch the rose that we see in the dream, and still we only dream. According to Delbœuf there is no valid criterion to show whether something is a dream or a conscious reality, except—and that only in practical generality—the fact of awakening. "I declare delusional everything that is experienced between the period of falling asleep and awakening, if I notice on awakening that I lie in my bed undressed" (p. 84). "I have considered the dream pictures real during sleep in consequence of the mental habit, which cannot be put to sleep, of perceiving an outer world with which I can contrast my ego."9
As the deviation from the outer world is taken as the stamp for the most striking characteristics of the dream, it will be worth while mentioning some ingenious observations of old Burdach8 which will throw light on the relation of the sleeping mind to the outer world and at the same time serve to prevent us from over-estimating the above deductions. "Sleep results only under the condition," says Burdach, "that the mind is not excited by sensory stimuli... but it is not the lack of sensory stimuli that conditions sleep, but rather a lack of interest for the same; some sensory impressions are even necessary in so far as they serve to calm the mind; thus the miller can fall asleep only when he hears the rattling of his mill, and he who finds it necessary to burn a light at night, as a matter of precaution, cannot fall asleep in the dark" (p. 457).
"The psyche isolates itself during sleep from the outer world, and withdraws from the periphery.... Nevertheless, the connection is not entirely interrupted; if one did not hear and feel even during sleep, but only after awakening, he would certainly never awake. The continuance of sensation is even more plainly shown by the fact that we are not always awakened by the mere sensory force of the impression, but by the psychic relation of the same; an indifferent word does not arouse the sleeper, but if called by name he awakens...: hence the psyche differentiates sensations during sleep.... It is for this reason that we may be awakened by the lack of a sensory stimulus if it relates to the presentation of an important thing; thus one awakens when the light is extinguished, and the miller when the mill comes to a standstill; that is, the awakening is due to the cessation of a sensory activity, which presupposes that it has been perceived, and that it has not disturbed the mind, being indifferent or rather gratifying" (p. 460, &c.).
If we are willing to disregard these objections, which are not to be taken lightly, we still must admit that the qualities of the dream life thus far considered, which originate by withdrawing from the outer world, cannot fully explain the strangeness of the dream. For otherwise it would be possible to change back the hallucinations of the dream into presentations and the situations of the dream into thoughts, and thus to perform the task of dream interpretation. Now this is what we do when we reproduce the dream from memory after awakening, and whether we are fully or only partially successful in this back translation the dream still retains its mysteriousness undiminished.
Furthermore all the authors assume unhesitatingly that still other more far-reaching alterations take place in the presentation material of waking life. One of them, Strümpell,66 expresses himself as follows (p. 17): "With the cessation of the objectively active outlook and of the normal consciousness, the psyche loses the foundation in which were rooted the feelings, desires, interests, and actions. Those psychic states, feelings, interests, estimates which cling in the waking state to the memory pictures also succumb to... an obscure pressure, in consequence of which their connection with the pictures becomes severed; the perception pictures of things, persons, localities, events, and actions of the waking state are singly very abundantly reproduced, but none of these brings along its psychic value. The latter is removed from them, and hence they float about in the mind dependent upon their own resources...."
This deprivation the picture surfers of its psychic value, which again goes back to the derivation from the outer world, is according to Strümpell mainly responsible for the impression of strangeness with which the dream is confronted in our memory.
We have heard that even falling asleep carries with it the abandonment of one of the psychic activities—namely, the voluntary conduct of the presentation course. Thus the supposition, suggested also by other grounds, obtrudes itself, that the sleeping state
