To designate the dream as a physical process, which for all that remains an activity of the mental organ, has still another sense. It is meant to dispute the dignity of a psychic process for the dream. The application to the dream of the very old comparison of the "ten fingers of a musically ignorant person running over the keyboard of an instrument," perhaps best illustrates in what estimation the dream activity has been held by the representatives of exact science. In this sense it becomes something entirely untranslatable, for how could the ten fingers of an unmusical player produce any music?
The theory of partial wakefulness has not passed without objection even in early times. Thus Burdach, in 1830, says: "If we say that the dream is a partial wakefulness, in the first place, we explain thereby neither the waking nor the sleeping state; secondly, this expresses nothing more than that certain forces of the mind are active in the dream while others are at rest. But such irregularities take place throughout life..." (p. 483).
Among extant dream theories which consider the dream a "physical" process, there is one very interesting conception of the dream, first propounded by Robert in 1866, which is attractive because it assigns to the dream a function or a useful end. As a basis for this theory, Robert takes from observation two facts which we have already discussed in our consideration of the dream material (see p. 13). These facts are: that one very often dreams about the insignificant impressions of the day, and that one rarely carries over into the dream the absorbing interests of the day. Robert asserts as exclusively correct, that things which have been fully settled never become dream inciters, but only such things as are incomplete in the mind or touch it fleetingly (p. 11). "We cannot usually explain our dreams because their causes are to be found in sensory impressions of the preceding day which have not attained sufficient recognition by the dreamer." The conditions allowing an impression to reach the dream are therefore, either that this impression has been disturbed in its elaboration, or that being too insignificant it has no claim to such elaboration.
Robert therefore conceives the dream "as a physical process of elimination which has reached to cognition in the psychic manifestation of its reaction." Dreams are eliminations of thoughts nipped in the bud. "A man deprived of the capacity for dreaming would surely in time become mentally unbalanced, because an immense number of unfinished and unsolved thoughts and superficial impressions would accumulate in his brain, under the pressure of which there would be crushed all that should be incorporated as a finished whole into memory." The dream acts as a safety-valve for the overburdened brain. Dreams possess healing and unburdening properties (p. 32).
It would be a mistake to ask Robert how representation in the dream can bring about an unburdening of the mind. The author apparently concluded from those two peculiarities of the dream material that during sleep such ejection of worthless impressions is effected as a somatic process, and that dreaming is not a special psychic process but only the knowledge that we receive of such elimination. To be sure an elimination is not the only thing that takes place in the mind during sleep. Robert himself adds that the incitements of the day are also elaborated, and "what cannot be eliminated from the undigested thought material lying in the mind becomes connected by threads of thought borrowed from the phantasy into a finished whole, and thus enrolled in the memory as a harmless phantasy picture " (p. 23).
But it is in his criticism of the dream sources that Robert appears most bluntly opposed to the ruling theory. Whereas according to the existing theory there would be no dream if the outer and inner sensory stimuli did not repeatedly wake the mind, according to Robert the impulse to dream lies in the mind itself. It lies in the overcharging which demands discharge, and Robert judges with perfect consistency when he maintains that the causes determining the dream which depend on the physical state assume a subordinate rank, and could not incite dreams in a mind containing no material for dream formation taken from waking consciousness. It is admitted, however, that the phantasy pictures originating in the depths of the mind can be influenced by the nervous stimuli (p. 48). Thus, according to Robert, the dream is not quite so dependent on the somatic element. To be sure, it is not a psychic process, and has no place among the psychic processes of the waking state; it is a nocturnal somatic process in the apparatus devoted to mental activity, and has a function to perform, viz. to guard this apparatus against overstraining, or, if the comparison may be changed, to cleanse the mind.
Another author, Yves Delage, bases his theory on the same characteristics of the dream, which become clear in the selection of the dream material, and it is instructive to observe how a slight turn in the conception of the same things gives a final result of quite different bearing.
Delage, after having lost through death a person very dear to him, found from his own experience that we do not dream of what occupies us intently during the day, or that we begin to dream of it only after it is overshadowed by other interests of the day. His investigations among other persons corroborated the universality of this state of affairs. Delage makes a nice observation of this kind, if it turn out to be generally true, about the dreaming of newly married people: "S'ils ont été fortement épris, presque jamais ils n'ont réve l'un de l'autre avant le mariage ou pendant la lune de miel; et s'ils ont rêve d'amour c'est pour etre infidèles avec quelque personne indifférente ou odieuse." But what does one dream of? Delage recognises that the material occurring in our dreams consists of fragments and remnants of impressions from the days preceding and former times. All that appears in our dreams, what at first we may be inclined to consider creations of the dream life, proves on more thorough investigation to be unrecognised reproductions, "souvenir inconscient." But this presentation material shows a common character; it originates from impressions which have probably affected our senses more forcibly than our mind, or from which the attention has been deflected soon after their appearance. The less conscious, and at the same time the stronger the impression, the more prospect it has of playing a part in the next dream.
These are essentially the same two categories of impressions, the insignificant and the unadjusted, which were emphasized by Robert, but Delage changes the connection by assuming that these impressions become the subject of dreams, not because they are indifferent, but because they are unadjusted. The insignificant impressions, too, are in a way not fully adjusted; they, too, are from their nature as new impressions "autant de ressorts tendus," which will be relaxed during sleep. Still more entitled to a rôle in the dream than the weak and almost unnoticed impression is a strong impression which has been accidentally detained in its elaboration or intentionally repressed. The psychic energy accumulated during the day through inhibition or suppression becomes the main-spring of the dream at night.
Unfortunately Delage stops here in his train of thought; he can ascribe only the smallest part to an independent psychic activity in the dream, and thus in his dream theory reverts to the ruling doctrine of a partial sleep of the brain: "En somme le rêve est le produit de la pensée errante, sans but et sans direction, se fixant successivement sur les souvenirs, qui ont gardé assez d'intensité pour se placer sur sa route et l'arrêter au passage, établissant entre eux un lien tantôt faible et indécis, tantôt plus fort et plus serré, selon que l'activité actuelle du cerveau est plus ou moins abolie par le sommeil."
In a third group we may include those dream theories which ascribe to the dreaming mind the capacity and propensity for a special psychic activity, which in the waking state it can accomplish either not at all or only in an imperfect manner. From the activity of these capacities there usually results a useful function of the dream. The dignity bestowed