We have already become acquainted with many conceptions of the dream which, more or less, merit the name of dream theories in this sense. The belief of the ancients that the dream was sent by the gods in order to guide the actions of man was a complete theory of the dream giving information concerning everything in the dream worth knowing. Since the dream has become an object of biological investigation we have a greater number of theories, of which, however, some are very incomplete.
If we waive completeness, we may attempt the following loose grouping of dream theories based on their fundamental conception of the degree and mode of the psychic activity in the dream:—
1 Theories, like those of Delbœuf,16 which allow the full psychic activity of the waking state to continue into the dream. Here the mind does not sleep; its apparatus remains intact, and, being placed under the conditions different from the waking state, it must in normal activity furnish results different from those of the waking state. In these theories it is a question whether they are in position to derive the distinctions between dreaming and waking thought altogether from the determinations of the sleeping state. They moreover lack a possible access to a function of the dream; one cannot understand why one dreams, why the complicated mechanism of the psychic apparatus continues to play even when it is placed under conditions for which it is not apparently adapted. There remain only two expedient reactions—to sleep dreamlessly or to awake when approached by disturbing stimuli—instead of the third, that of dreaming.
2 Theories which, on the contrary, assume for the dream a diminution for the psychic activity, a loosening of the connections, and an impoverishment in available material. In accordance with these theories, one must assume for sleep a psychological character entirely different from the one given by Delbœuf. Sleep extends far beyond the mind—it does not consist merely in a shutting off of the mind from the outer world; on the contrary, it penetrates into its mechanism, causing it at times to become useless. If I may draw a comparison from psychiatrical material, I may say that the first theories construct the dream like a paranoia, while the second make it after the model of a dementia or an amentia.
The theory that only a fragment of the psychic activity paralysed by sleep comes to expression is by far the favourite among the medical writers and in the scientific world. As far as one may presuppose a more general interest in dream interpretation, it may well be designated as the ruling theory of the dream. It is to be emphasized with what facility this particular theory escapes the worst rock threatening every dream interpretation, that is to say, being shipwrecked upon one of the contrasts embodied in the dream. As this theory considers the dream the result of a partial waking (or as Herbart's Psychology of the dream says, "a gradual, partial, and at the same time very anomalous waking"), it succeeds in covering the entire series of inferior activities in the dream which reveal themselves in its absurdities, up to the full concentration of mental activity, by following a series of states which become more and more awake until they reach full awakening.
One who finds the psychological mode of expression indispensable, or who thinks more scientifically, will find this theory of the dream expressed in the discussion of Binz4 (p. 43):—
"This state [of numbness], however, gradually approaches its end in the early morning hours. The accumulated material of fatigue in the albumen of the brain gradually becomes less. It is gradually decomposed or carried away by the constantly flowing circulation. Here and there some masses of cells can be distinguished as awake, while all around everything still remains in a state of torpidity. The isolated work of the individual groups now appears before our clouded consciousness, which lacks the control of other parts of the brain governing the associations. Hence the pictures created, which mostly correspond to the objective impressions of the recent past, fit with each other in a wild and irregular manner. The number of the brain cells set free becomes constantly greater, the irrationality of the dream constantly less."
The conception of the dream as an incomplete, partial waking state, or traces of its influence, can surely be found among all modern physiologists and philosophers. It is most completely represented by Maury.48 It often seems as if this author represented to himself the state of being awake or asleep in anatomical regions; at any rate it appears to him that an anatomical province is connected with a definite psychic function. I may here merely mention that if the theory of partial waking could be confirmed, there would remain much to be accomplished in its elaboration.
Naturally a function of the dream cannot be found in this conception of the dream life. On the contrary, the criticism of the status and importance of the dream is consistently uttered in this statement of Binz (p. 357): "All the facts, as we see, urge us to characterise the dream as a physical process in all cases useless, in many cases even morbid."
The expression "physical" in reference to the dream, which owes its prominence to this author, points in more than one direction. In the first place, it refers to the etiology of the dream, which was especially clear to Binz, as he studied the experimental production of dreams by the administration of poisons. It is certainly in keeping with this kind of dream theory to ascribe the incitement of the dream exclusively to somatic origin whenever possible. Presented in the most extreme form, it reads as follows: After we have put ourselves to sleep by removing the stimuli, there would be no need and no occasion for dreaming until morning, when the gradual awakening through the incoming stimuli would be reflected in the phenomenon of dreaming. But as a matter of fact, it is not possible to keep sleep free from stimuli; just as Mephisto complains about the germs of life, so stimuli reach the sleeper from every side—from without, from within, and even from certain bodily regions which never give us any concern during the waking state. Thus sleep is disturbed; the mind is aroused, now by this, now by that little thing, and functionates for a while with the awakened part only to be glad to fall asleep again. The dream is a reaction to the stimulus causing a disturbance of sleep—to be sure, it is a purely superfluous reaction.
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,8 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 Robert55 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."