I. THE SCIENTIFIC LITERATURE ON THE PROBLEMS OF THE DREAM

(a) The Relation of the Dream to the Waking State

The naïve judgment of a person on awakening assumes that the dream—if indeed it does not originate in another world—at any rate has taken the dreamer into another world. The old physiologist, Burdach,⁸ to whom we are indebted for a careful and discriminating description of the phenomena of dreams, expressed this conviction in an often-quoted passage, p. 474: "The waking life never repeats itself with its trials and joys, its pleasures and pains, but, on the contrary, the dream aims to relieve us of these. Even when our whole mind is filled with one subject, when profound sorrow has torn our hearts or when a task has claimed the whole power of our mentality, the dream either gives us something entirely strange, or it takes for its combinations only a few elements from reality, or it only enters into the strain of our mood and symbolises reality."

L. Strümpell⁶⁶ expresses himself to the same effect in his Nature and Origin of Dreams (p. 16), a study which is everywhere justly held in high respect: "He who dreams turns his back upon the world of waking consciousness" (p. 17). "In the dream the memory of the orderly content of the waking consciousness and its normal behaviour is as good as entirely lost" (p. 19). "The almost complete isolation of the mind in the dream from the regular normal content and course of the waking state..."

But the overwhelming majority of the authors have assumed a contrary view of the relation of the dream to waking life. Thus Haffner³² (p. 19): "First of all the dream is the continuation of the waking state. Our dreams always unite themselves with those ideas which have shortly before been in our consciousness. Careful examination will nearly always find a thread by which the dream has connected itself with the experience of the previous day." Weygandt⁷⁵ (p. 6), flatly contradicts the above cited statement of Burdach: "For it may often be observed, apparently in the great majority of dreams, that they lead us directly back into everyday life, instead of releasing us from it." Maury⁴⁸ (p. 56), says in a concise formula: "Nous rêvons de ce que nous avons vu, dit, désiré ou fait." Jessen,³⁶ in his Psychology, published in 1855 (p. 530), is somewhat more explicit: "The content of dreams is more or less determined by the individual personality, by age, sex, station in life, education, habits, and by events and experiences of the whole past life."

The ancients had the same idea about the dependence of the dream content upon life. I cite Radestock⁵⁴ (p. 139): "When Xerxes, before his march against Greece, was dissuaded from this resolution by good counsel, but was again and again incited by dreams to undertake it, one of the old rational dream-interpreters of the Persians, Artabanus, told him very appropriately that dream pictures mostly contain that of which one has been thinking while awake."

In the didactic poem of Lucretius, De Rerum Natura (IV, v. 959), occurs this passage:—

"Et quo quisque fere studio devinctus adhaeret,
aut quibus in rebus multum sumus ante morati
atque in ea ratione fuit contenta magis mens,
in somnis eadem plerumque videmur obire;
causidici causas agere et componere leges,
induperatores pugnare ac proelia obire," &c., &c.

Cicero (De Divinatione, II) says quite similarly, as does also Maury much later:—

"Maximeque reliquiae earum rerum moventur in animis et agitantur, de quibus vigilantes aut cogitavimus aut egimus."

The contradiction expressed in these two views as to the relation between dream life and waking life seems indeed insoluble. It will therefore not be out of place to mention the description of F. W. Hildebrandt³⁵ (1875), who believes that the peculiarities of the dream can generally be described only by calling them a "series of contrasts which apparently shade off into contradictions" (p. 8). "The first of these contrasts is formed on the one hand by the strict isolation or seclusion of the dream from true and actual life, and on the other hand by the continuous encroachment of the one upon the other, and the constant dependency of one upon the other. The dream is something absolutely separated from the reality experienced during the waking state; one may call it an existence hermetically sealed up and separated from real life by an unsurmountable chasm. It frees us from reality, extinguishes normal recollection of reality, and places us in another world and in a totally different life, which at bottom has nothing in common with reality..." Hildebrandt then asserts that in falling asleep our whole being, with all its forms of existence, disappears "as through an invisible trap door."

"Nevertheless," continues Hildebrandt, "the opposite is seemingly just as true and correct. I believe that hand in hand with this seclusion and isolation there can still exist the most intimate relation and connection. We may justly say that no matter what the dream offers, it finds its material in reality and in the psychic life arrayed around this reality. However strange the dream may seem, it can never detach itself from reality, and its most sublime as well as its most farcical structures must always borrow their elementary material either from what we have seen with our eyes in the outer world, or from what has previously found a place somewhere in our waking thoughts; in other words, it must be taken from what we had already experienced either objectively or subjectively."

(b) The Material of the Dream.—Memory in the Dream

That all the material composing the content of the dream in some way originates in experience, that it is reproduced in the dream, or recalled,—this at least may be taken as an indisputable truth. Yet it would be wrong to assume that such connection between dream content and reality will be readily disclosed as an obvious product of the instituted comparison. On the contrary, the connection must be carefully sought, and in many cases it succeeds in eluding discovery for a long time. The reason for this is to be found in a number of peculiarities evinced by the memory in dreams, which, though universally known, have hitherto entirely eluded explanation.

It often happens that matter appears in the dream content which one cannot recognise later in the waking state as belonging to one's knowledge and experience. One remembers well enough having dreamed about the subject in question, but cannot recall the fact or time of the experience. The dreamer is therefore in the dark as to the source from which the dream has been drawing, and is even tempted to believe an independently productive activity on the part of the dream, until, often long afterwards, a new episode brings back to recollection a former experience given up as lost, and thus reveals the source of the dream. One is thus forced to admit that something has been known and remembered in the dream that has been withdrawn from memory during the waking state.

Delbœuf¹⁶ narrates from his own experience an especially impressive example of this kind. He saw in his dream the courtyard of his house covered with snow, and found two little lizards half-frozen and buried in the snow. Being a lover of animals, he picked them up, warmed them, and put them back into a crevice in the wall which was reserved for them. He also gave them some small fern leaves that had been growing on the wall, which he knew they were fond of. In the dream he knew the name of the plant: Asplenium ruta muralis. The dream then continued, returning after a digression to the lizards, and to his astonishment Delbœuf saw two other little animals falling upon what was left of the ferns. On turning his eyes to the open field he saw a fifth and a sixth lizard running into the hole in the wall, and finally the street was covered with a procession of lizards, all wandering in the same direction, &c.

In his waking state Delbœuf knew only a few Latin names of plants, and nothing of the Asplenium. To his great surprise he became convinced that a fern of this name really existed and that the correct name was Asplenium ruta muraria, which the dream had slightly disfigured. An accidental coincidence could hardly be considered, but it remained a mystery for Delbœuf whence he got his knowledge of the name Asplenium in the dream.

The dream occurred in 1862. Sixteen years later, while at the house of one of his friends, the philosopher noticed a small album containing dried plants resembling the albums that are sold as souvenirs to visitors in many parts of Switzerland. A sudden recollection occurred to him; he opened the herbarium, and discovered therein the Asplenium of his dream, and recognised his own handwriting in the accompanying Latin name. The connection could now be traced. While on her wedding trip, a sister of this friend visited Delbœuf in 1860—two years prior to the lizard dream. She had with her at the time this album, which was intended for her brother, and Delbœuf took the trouble to write, at the dictation of a botanist, under each of the dried plants the Latin name.

That the dream has at its disposal recollections which are inaccessible to the waking state is such a remarkable and theoretically important fact that I should like to urge more attention to it by reporting several other "Hypermnesic Dreams." Maury⁴⁸ relates that for some time the word Mussidan used to occur to his mind during the day. He knew it to be the name of a French city, but nothing else. One night he dreamed of a conversation with a certain person who told him that she came from Mussidan, and, in answer to his question where the city was, she replied: "Mussidan is a principal country town in the Département de La Dordogne." On waking, Maury put no faith in the information received in his dream; the geographical lexicon, however, showed it to be perfectly correct. In this case the superior knowledge of the dream is confirmed, but the forgotten source of this knowledge has not been traced.

Jessen³⁶ tells (p. 55) of a quite similar dream occurrence, from more remote times. Among others we may here mention the dream of the elder Scaliger (Hennings, l.c., p. 300), who wrote a poem in praise of celebrated men of Verona, and to whom a man, named Brugnolus, appeared in a dream, complaining that he had been neglected. Though Scaliger did not recall ever having heard of him, he wrote some verses in his honour, and his son later discovered at Verona that a Brugnolus had formerly been famous there as a critic.

Myers is said to have published a whole collection of such hypermnesic dreams in the Proceedings of the Society for Psychical Research, which are unfortunately inaccessible to me. I believe every one who occupies himself with dreams will recognise as a very common phenomenon the fact that the dream gives proof of knowing and recollecting matters unknown to the waking person. In my psychoanalytic investigations of nervous patients, of which I shall speak later, I am every week more than once in position to convince my patients from their dreams that they are well acquainted with quotations, obscene expressions, &c., and that they make use of these in their dreams, although they have forgotten them in the waking state. I shall cite here a simple case of dream hypermnesia because it was easy to trace the source which made the knowledge accessible to the dream.

A patient dreamed in a lengthy connection that he ordered a "Kontuszówka" in a café, and after reporting this inquired what it might mean, as he never heard the name before. I was able to answer that Kontuszówka was a Polish liquor which he could not have invented in his dream, as the name had long been familiar to me in advertisements. The patient would not at first believe me, but some days later, after he had realised his dream of the café, he noticed the name on a signboard at the street corner, which he had been obliged to pass for months at least twice a day.

One of the sources from which the dream draws material for reproduction—material which in part is not recalled or employed in waking thought—is to be found in childhood. I shall merely cite some of the authors who have observed and emphasized this.

Hildebrandt³⁵ (p. 23): "It has already been expressly admitted that the dream sometimes brings back to the mind with wonderful reproductive ability remote and even forgotten experiences from the earliest periods."

Strümpell⁶⁶ (p. 40): "The subject becomes more interesting when we remember how the dream sometimes brings forth, as it were, from among the deepest and heaviest strata which later years have piled upon the earliest childhood experiences, the pictures of certain places, things, and persons, quite uninjured and with their original freshness."

Volkelt⁷² (p. 119): "It is essentially noteworthy how easily infantile and youthful reminiscences enter into the dream. What we have long ceased to think about, what has long since lost for us all importance, is constantly recalled by the dream."

The sway of the dream over the infantile material, which, as is well known, mostly occupies the gaps in the conscious memory, causes the origin of interesting hypermnestic dreams, a few of which I shall here report.

Maury⁴⁸ relates (p. 92) that as a child he often went from his native city, Meaux, to the neighbouring Trilport, where his father superintended the construction of a bridge. On a certain night a dream transported him to Trilport, and he was again playing in the city streets. A man approached him wearing some sort of uniform. Maury asked him his name, and he introduced himself, saying that his name was C——, and that he was a bridge guard. On waking, Maury, who still doubted the reality of the reminiscence, asked his old servant, who had been with him in his childhood, whether she remembered a man of this name. "Certainly," was the answer, "he used to be watchman on the bridge which your father was building at that time."

As if to counterbalance the immense rôle ascribed to the infantile impressions in the dream, many authors assert that the majority of dreams show elements from the most recent time. Thus Robert⁵⁵ (p. 46) declares that the normal dream generally occupies itself only with the impressions of the recent days. Nelson,⁵⁰ an American author, thinks that the impressions most frequently found in the dream date from two or three days before, as if the impressions of the day immediately preceding the dream were not sufficiently weakened and remote.

Many authors who are convinced of the intimate connection between the dream content and the waking state are impressed by the fact that impressions which have intensely occupied the waking mind appear in the dream only after they have been to some extent pushed aside from the elaboration of the waking thought. Thus, as a rule, we do not dream of a dead beloved person while we are still overwhelmed with sorrow. Still Miss Hallam,³³ one of the latest observers, has collected examples showing the very opposite behaviour, and claims for the point the right of individual psychology.

The third and the most remarkable and incomprehensible peculiarity of the memory in dreams, is shown in the selection of the reproduced material, for stress is laid not only on the most significant, but also on the most indifferent and superficial reminiscences. On this point I shall quote those authors who have expressed their surprise in the most emphatic manner.

Hildebrandt³⁵ (p. 11): "For it is a remarkable fact that dreams do not, as a rule, take their elements from great and deep-rooted events or from the powerful and urgent interests of the preceding day, but from unimportant matters, from the most worthless fragments of recent experience or of a more remote past."

Strümpell⁶⁶ (p. 39): "... such cases where the analysis of a dream brings to light elements which, although derived from events of the previous day or the day before the last, yet prove to be so unimportant and worthless for the waking state that they merge into forgetfulness shortly after coming to light."

Havelock Ellis²³ (p. 727): "The profound emotions of waking life, the questions and problems on which we spread our chief voluntary mental energy, are not those which 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."

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.

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.^F

(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. Science 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.

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 anæsthesia 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 the bed with our feet extending beyond the edge, we may dream of standing on the brink of a terrifying precipice, or of falling from a steep height. Should our head accidentally get under the pillow we may then imagine a big rock hanging over us and about to crush us under its weight. Accumulation of semen produces voluptuous dreams, and local pain the idea of suffering ill treatment, of hostile attacks, or of accidental bodily injuries."

"Meier (Versuch einer Erklärung des Nachtwandelns, Halle, 1758, p. 33), once dreamed of being assaulted by several persons who threw him flat on the ground and drove a stake into the ground between his big and second toes. While imagining this in his dream he suddenly awoke and felt a blade of straw sticking between his toes... Gregory relates that he once applied a hot-water bottle to his feet, and dreamed of taking a trip to the summit of Mount Ætna, where he found the heat on the ground almost unbearable. After having applied a blistering plaster to his head, a second man dreamed of being scalped by Indians; a third, whose shirt was damp, dreamed of being dragged through a stream. An attack of gout caused the patient to believe that he was in the hands of the Inquisition, and suffering pains of torture (Macnish)."

Maury⁴⁸ reports new observations on dreams produced in himself. (A number of other attempts produced no results.)

• 1. He was tickled with a feather on his lips and on the tip of his nose. He dreamed of awful torture, viz. that a mask of pitch was stuck to his face and then forcibly torn off, taking the skin with it.
• 2. Scissors were sharpened on pincers. He heard bells ringing, then sounds of alarm which took him back to the June days of 1848.
• 3. Cologne water was put on his nose. He found himself in Cairo in the shop of John Maria Farina. This was followed by mad adventures which he was unable to reproduce.
• 4. His neck was lightly pinched. He dreamed that a blistering plaster was put on him, and thought of a doctor who treated him in his childhood.
• 5. A hot iron was brought near his face. He dreamed that chauffeurs^G broke into the house and forced the occupants to give up their money by sticking their feet into burning coals. The Duchess of Abrantés, whose secretary he imagined himself in the dream, then entered.
• 6. A drop of water was let fall on his forehead. He imagined himself in Italy perspiring heavily and drinking white wine of Orvieto.
• 7. When a burning candle was repeatedly focussed on him through red paper, he dreamed of the weather, of heat, and of a storm at sea which he once experienced in the English Channel.

D'Hervey,³⁴ Weygandt,⁷⁵ and others have made other attempts to produce dreams experimentally.

Many have observed the striking skill of the dream in interweaving into its structure sudden impressions from the outer world in such a manner as to present a gradually prepared and initiated catastrophe (Hildebrandt)³⁵. "In former years," this author relates, "I occasionally made use of an alarm clock in order to wake regularly at a certain hour in the morning. It probably happened hundreds of times that the sound of this instrument fitted into an apparently very long and connected dream, as if the entire dream had been especially designed for it, as if it found in this sound its appropriate and logically indispensable point, its inevitable issue."

The following dream of Maury⁴⁸ has become celebrated. He was sick, and remained in bed; his mother sat beside him. He then dreamed of the reign of terror at the time of the Revolution. He took part in terrible scenes of murder, and finally he himself was summoned before the Tribunal. There he saw Robespierre, Marat, Fouquier-Tinville, and all the sorry heroes of that cruel epoch; he had to give an account of himself, and, after all sort of incidents which did not fix themselves in his memory, he was sentenced to death. Accompanied by an enormous crowd, he was led to the place of execution. He mounted the scaffold, the executioner tied him to the board, it tipped, and the knife of the guillotine fell. He felt his head severed from the trunk, and awakened in terrible anxiety, only to find that the top piece of the bed had fallen down, and had actually struck his cervical vertebra in the same manner as the knife of a guillotine.

This dream gave rise to an interesting discussion introduced by Le Lorrain⁴⁵ and Egger²⁰ in the Revue Philosophique. The question was whether, and how, it was possible for the dreamer to crowd together an amount of dream content apparently so large in the short space of time elapsing between the perception of the waking stimulus and the awakening.

Examples of this nature make it appear that the objective stimuli during sleep are the most firmly established of all the dream sources; indeed, it is the only stimulus which plays any part in the layman's knowledge. Scientific investigation cannot, however, stop here, but is incited to further research by the observation that the stimulus influencing the senses during sleep does not appear in the dream at all in its true form, but is replaced by some other presentation which is in some way related to it. But the relation existing between the stimulus and the result of the dream is, according to Maury,⁴⁷ "une affinité quelconque mais qui n'est pas unique et exclusive" (p. 72). If we read, e.g., three of Hildebrandt's "Alarm Clock Dreams," we will then have to inquire why the same stimulus evoked so many different results, and why just these results and no others.

The question why the dreaming mind misjudges the nature of the objective sensory stimulus has been answered by Strümpell,⁶⁶ and almost identically by Wundt,⁷⁶ to the effect that the reaction of the mind to the attacking stimuli in sleep is determined by the formation of illusions. A sensory impression is recognised by us and correctly interpreted, i.e. it is classed with the memory group to which it belongs according to all previous experience, if the impression is strong, clear, and long enough, and if we have the necessary time at our disposal for this reflection. If these conditions are not fulfilled, we mistake the objects which give rise to the impression, and on its basis we form an illusion. "If one takes a walk in an open field and perceives indistinctly a distant object, it may happen that he will at first take it for a horse." On closer inspection the image of a cow resting may obtrude itself, and the presentation may finally resolve itself with certainty into a group of people sitting. The impressions which the mind receives during sleep through outer stimuli are of a similar indistinct nature; they give rise to illusions because the impression evokes a greater or lesser number of memory pictures through which the impression receives its psychic value. In which of the many spheres of memory to be taken into consideration the corresponding pictures are aroused, and which of the possible association connections thereby come into force, this, even according to Strümpell, remains indeterminable, and is left, as it were, to the caprice of the psychic life.

We may here take our choice. We may admit that the laws of the dream formation cannot really be traced any further, and therefore refrain from asking whether or not the interpretation of the illusion evoked by the sensory impression depends upon still other conditions; or we may suppose that the objective sensory stimulus encroaching upon sleep plays only a modest part as a dream source, and that other factors determine the choice of the memory picture to be evoked. Indeed, on carefully examining Maury's experimentally produced dreams, which I have purposely reported in detail, one is apt to think that the experiment really explains the origin of only one of the dream elements, and that the rest of the dream content appears in fact too independent, too much determined in detail, to be explained by the one demand, viz. that it must agree with the element experimentally introduced. Indeed one even begins to doubt the illusion theory, and the power of the objective impression to form the dream, when one learns that this impression at times experiences the most peculiar and far-fetched interpretations during the sleeping state. Thus B. M. Simon⁶³ tells of a dream in which he saw persons of gigantic stature^H seated at a table, and heard distinctly the awful rattling produced by the impact of their jaws while chewing. On waking he heard the clacking of the hoofs of a horse galloping past his window.

II. Internal (Subjective) Sensory Stimuli.—Notwithstanding all objections to the contrary, we must admit that the rôle of the objective sensory stimuli as a producer of dreams has been indisputably established, and if these stimuli seem perhaps insufficient in their nature and frequency to explain all dream pictures, we are then directed to look for other dream sources acting in an analogous manner. I do not know where the idea originated that along with the outer sensory stimuli the inner (subjective) stimuli should also be considered, but as a matter of fact this is done more or less fully in all the more recent descriptions of the etiology of dreams. "An important part is played in dream illusions," says Wundt³⁶ (p. 363), "by those subjective sensations of seeing and hearing which are familiar to us in the waking state as a luminous chaos in the dark field of vision, ringing, buzzing, &c., of the ears, and especially irritation of the retina. This explains the remarkable tendency of the dream to delude the eyes with numbers of similar or identical objects. Thus we see spread before our eyes numberless birds, butterflies, fishes, coloured beads, flowers, &c. Here the luminous dust in the dark field of vision has taken on phantastic figures, and the many luminous points of which it consists are embodied by the dream in as many single pictures, which are looked upon as moving objects owing to the mobility of the luminous chaos."

The main proof for the dream-inciting power of subjective sensory excitements is offered by the so-called hypnogogic hallucinations, which have been described by John Müller as "phantastic visual manifestations." They are those very vivid and changeable pictures which occur regularly in many people during the period of falling asleep, and which may remain for awhile even after the eyes have been opened. Maury,⁴⁸ who was considerably troubled by them, subjected them to a thorough study, and maintained that they are related to or rather identical with dream pictures—this has already been asserted by John Müller. Maury states that a certain psychic passivity is necessary for their origin; it requires a relaxation of the tension of attention (p. 59). According to Maury, if one awakens shortly thereafter, it is often possible to demonstrate the same pictures in the dream which one has perceived as hypnogogic hallucinations before falling asleep (p. 134). Thus it once happened to Maury with a group of pictures of grotesque figures, with distorted features and strange headdresses, which obtruded themselves upon him with incredible importunity during the period of falling asleep, and which he recalled having dreamed upon awakening.

A more recent observer of hypnogogic hallucinations, G. Trumbull Ladd,⁴⁰ takes the same path pursued by John Müller and Maury. By dint of practice he succeeded in acquiring the faculty of suddenly arousing himself, without opening his eyes, two to five minutes after having gradually fallen asleep, which gave him opportunity to compare the sensations of the retina just vanishing with the dream pictures remaining in his memory. He assures us that an intimate relation between the two can always be recognised, in the sense that the luminous dots and lines of the spontaneous light of the retina produced, so to speak, the sketched outline or scheme for the psychically perceived dream figures. A dream, e.g., in which he saw in front of him clearly printed lines which he read and studied, corresponded to an arrangement of the luminous dots and lines in the retina in parallel lines. Without in any way under-estimating the central part of the phenomenon, Ladd believes that hardly any visual dream occurs in our minds that is not based on material furnished by this inner condition of stimulation in the retina. This is particularly true of dreams occurring shortly after falling asleep in a dark room, while dreams occurring in the morning near the period of awakening receive their stimulation from the objective light penetrating the eye from the lightened room.

III. Internal (Organic) Physical Excitation.—If we are disposed to seek dream sources not outside, but inside, the organism, we must remember that almost all our internal organs, which in their healthy state hardly remind us of their existence, may, in states of excitation—as we call them—or in disease, become for us a source of the most painful sensations, which must be put on an equality with the external excitants of the pain and sensory stimuli. It is on the strength of very old experience that, e.g., Strümpell⁶⁶ declares that "during sleep the mind becomes far more deeply and broadly conscious of its connection with the body than in the waking state, and it is compelled to receive and be influenced by stimulating impressions originating in parts and changes of the body of which it is unconscious in the waking state." Even Aristotle¹ declares it quite possible that the dream should draw our attention to incipient morbid conditions which we have not noticed at all in the waking state owing to the exaggeration given by the dream to the impressions; and some medical authors, who were certainly far from believing in any prophetic power of the dream, have admitted this significance of the dream at least for the foretelling of disease. (Compare M. Simon, p. 31, and many older authors.)

Even in our times there seems to be no lack of authenticated examples of such diagnostic performances on the part of the dream. Thus Tissié⁶⁸ cites from Artigues (Essai sur la Valeur séméiologique des Réves), the history of a woman of forty-three years, who, during several years of apparently perfect health, was troubled with anxiety dreams, and in whom medical examination later disclosed an incipient affection of the heart to which she soon succumbed.

Serious disturbances of the internal organs apparently act as inciters of dreams in a considerable number of persons. Attention is quite generally called to the frequency of anxiety dreams in the diseases of the heart and lungs; indeed this relation of the dream life is placed so conspicuously in the foreground by many authors that I shall here content myself with a mere reference to the literature. (Radestock,⁵⁴ Spitta,⁶⁴ Maury, M. Simon, Tissié.) Tissié even assumes that the diseased organs impress upon the dream content their characteristic features. The dreams of persons suffering from diseases of the heart are generally very brief and terminate in a terrified awakening; the situation of death under terrible circumstances almost always plays a part in their content. Those suffering from diseases of the lungs dream of suffocation, of being crowded, and of flight, and a great many of them are subject to the well-known nightmare, which, by the way, Boerner has succeeded in producing experimentally by lying on the face and closing up the openings of the respiratory organs. In digestive disturbances the dream contains ideas from the sphere of enjoyment and disgust. Finally, the influence of sexual excitement on the dream content is perceptible enough in every one's experience, and lends the strongest support to the entire theory of the dream excitation through organic sensation.

But we need go only a step further to find a dream source which is more prolific than any of those mentioned above, which indeed promises to be inexhaustible in every case. If it is established that the bodily organs become in sickness an exciting source of dreams, and if we admit that the mind, diverted during sleep from the outer world, can devote more attention to the interior of the body, we may readily assume that the organs need not necessarily become diseased in order to permit stimuli, which in some way or other grow into dream pictures, to reach the sleeping mind. What in the waking state we broadly perceive as general sensation, distinguishable by its quality alone, to which, in the opinion of the physicians, all the organic systems contribute their shares—this general sensation at night attaining powerful efficiency and becoming active with its individual components—would naturally furnish the most powerful as well as the most common source for the production of the dream presentations.

The theory of the origin of dreams just stated has been the favourite with all medical authors. The obscurity which conceals the essence of our being—the "moi splanchnique," as Tissié terms it—from our knowledge and the obscurity of the origin of the dream correspond too well not to be brought into relation with each other. The train of thought which makes organic sensation the inciter of the dream has besides another attraction for the physician, inasmuch as it favours the etiological union of the dream and mental diseases, which show so many agreements in their manifestations, for alterations in the organic sensations and excitations emanating from the inner organs are both of wide significance in the origin of the psychoses. It is therefore not surprising that the theory of bodily sensation can be traced to more than one originator who has propounded it independently.

A number of authors have been influenced by the train of ideas developed by the philosopher Schopenhauer in 1851. Our conception of the universe originates through the fact that our intellect recasts the impressions coming to it from without in the moulds of time, space, and causality. The sensations from the interior of the organism, proceeding from the sympathetic nervous system, exert in the day-time an influence on our mood for the most part unconscious. At night, however, when the overwhelming influence of the day's impressions is no longer felt, the impressions pressing upward from the interior are able to gain attention—just as in the night we hear the rippling of the spring that was rendered inaudible by the noise of the day. In what other way, then, could the intellect react upon these stimuli than by performing its characteristic function? It will transform the stimuli into figures, filling space and time, which move at the beginning of causality; and thus the dream originates. Scherner,⁵⁸ and after him Volkelt,⁷² attempted to penetrate into closer relations between physical sensations and dream pictures.

In a study particularly logical in its development, the psychiatrist Krauss³⁹ found the origin of the dream as well as of deliria and delusions in the same element, viz. the organically determined sensation. According to this author there is hardly a place in the organism which might not become the starting point of a dream or of a delusion. Now organically determined sensations "may be divided into two classes: (1) those of the total feeling (general sensations), (2) specific sensations which are inherent in the principal systems of the vegetative organism, which may be divided into five groups: (a) the muscular, (b) the pneumatic, (c) the gastric, (d) the sexual, (e) the peripheral sensations (p. 33 of the second article)."

The origin of the dream picture on the basis of the physical sensations is conceived by Krauss as follows: The awakened sensation evokes a presentation related to it in accordance with some law of association, and combines with this, thus forming an organic structure, towards which, however, consciousness does not maintain its normal attitude. For it does not bestow any attention on the sensation itself, but concerns itself entirely with the accompanying presentation; this is likewise the reason why the state of affairs in question should have been so long misunderstood (p. 11, &c.). Krauss finds for this process the specific term of "transubstantiation of the feeling into dream pictures" (p. 24).

A certain agreement, however, is manifested in the interpretation of the various forms of dreams which have been designated as "typical" because they recur in so many persons with almost the same contents. Among these are the well-known dreams of falling from heights, of the falling out of teeth, of flying, and of embarrassment because of being naked or barely clad. This last dream is said to be caused simply by the perception felt in sleep that one has thrown off the bedcover and is exposed. The dream of the falling out of teeth is explained by "dental irritation," which does not, however, of necessity imply a morbid state of excitation in the teeth. According to Strümpell,⁶⁶ the flying dream is the adequate picture used by the mind to interpret the sum of excitation emanating from the rising and sinking of the pulmonary lobes after the cutaneous sensation of the thorax has been reduced to insensibility. Falling from a height in a dream is said to have its cause in the fact that when unconsciousness of the sensation of cutaneous pressure has set in, either an arm falls away from the body or a flexed knee is suddenly stretched out, causing the feeling of cutaneous pressure to return to consciousness, and the transition to consciousness embodies itself psychically as a dream of falling. (Strümpell, p. 118).

From comparison of a series of similar dreams, M. Simon⁶³ endeavoured to formulate certain rules for the influence of the organic sensations on the determination of the resulting dream. He says (p. 34): "If any organic apparatus, which during sleep normally participates in the expression of an affect, for any reason merges into the state of excitation to which it is usually aroused by that affect, the dream thus produced will contain presentations which fit the affect."

Another rule reads as follows (p. 35): "If an organic apparatus is in a state of activity, excitation, or disturbance during sleep, the dream will bring ideas which are related to the exercise of the organic function which is performed by that apparatus."

Mourly Vold⁷³ has undertaken to prove experimentally the influence assumed by the theory of bodily sensation for a single territory. He has made experiments in altering the positions of the sleeper's limbs, and has compared the resulting dream with his alterations. As a result he reports the following theories:—

• 1. The position of a limb in a dream corresponds approximately to that of reality, i.e. we dream of a static condition of the limb which corresponds to the real condition.
• 2. When one dreams of a moving limb it always happens that one of the positions occurring in the execution of this movement corresponds to the real position.
• 3. The position of one's own limb may be attributed in the dream to another person.
• 4. One may dream further that the movement in question is impeded.
• 5. The limb in any particular position may appear in the dream as an animal or monster, in which case a certain analogy between the two is established.
• 6. The position of a limb may incite in the dream ideas which bear some relation or other to this limb. Thus, e.g., if we are employed with the fingers we dream of numerals.

Such results would lead me to conclude that even the theory of bodily sensation cannot fully extinguish the apparent freedom in the determination of the dream picture to be awakened.^I

IV. Psychic Exciting Sources.—In treating the relations of the dream to the waking life and the origin of the dream material, we learned that the earliest as well as the latest investigators agreed that men dream of what they are doing in the day-time, and of what they are interested in during the waking state. This interest continuing from waking life into sleep, besides being a psychic tie joining the dream to life, also furnishes us a dream source not to be under-estimated, which, taken with those stimuli which become interesting and active during sleep, suffices to explain the origin of all dream pictures. But we have also heard the opposite of the above assertion, viz. that the dream takes the sleeper away from the interests of the day, and that in most cases we do not dream of things that have occupied our attention during the day until after they have lost for the waking life the stimulus of actuality.

If the conscious interest, together with the inner and outer sleep stimuli, sufficed to cover the etiology of the dreams, we ought to be in a position to give a satisfactory account of the origin of all the elements of a dream; the riddle of the dream sources would thus be solved, leaving only the task of separating the part played by the psychic and the somatic dream stimuli in individual dreams. But as a matter of fact no such complete solution of a dream has ever been accomplished in any case, and, what is more, every one attempting such solution has found that in most cases there have remained a great many components of the dream, the source of which he was unable to explain. The daily interest as a psychic source of dreams is evidently not far-reaching enough to justify the confident assertions to the effect that we all continue our waking affairs in the dream.

Other psychic sources of dreams are unknown. Hence, with the exception perhaps of the explanation of dreams given by Scherner,⁵⁸ all explanations found in the literature show a large gap when we come to the derivation of the material for the presentation pictures, which is most characteristic for the dream. In this dilemma the majority of authors have developed a tendency to depreciate as much as possible the psychic factor in the excitations of dreams which is so difficult to approach. Wundt, too, attempts to depreciate the psychic factor in the stimulation of dreams by declaring that the "phantasms of the dream certainly are unjustly regarded as pure hallucinations, and that probably most dream presentations are really illusions, inasmuch as they emanate from slight sensory impressions which are never extinguished during sleep" (p. 338, &c.). Weygandt⁷⁵ agrees with this view, but generalises it. He asserts that "the first source of all dream presentations is a sensory stimulus to which reproductive associations are then joined" (p. 17). Tissié⁶⁸ goes still further in repressing the psychic exciting sources (p. 183): "Les rêves d'origine absolument psychique n'existent pas"; and elsewhere (p. 6), "Les pensées de nos rêves nous viennent de dehors..."

We shall learn later that the riddle of the dream formation can be solved by the disclosure of an unsuspected psychic source of excitement. For the present we shall not be surprised at the over-estimation of those stimuli for the formation of the dream which do not originate from psychic life. It is not merely because they alone can easily be found and even confirmed by experiment, but the somatic conception of the origin of dreams thoroughly corresponds to the mode of thinking in vogue nowadays in psychiatry. Indeed, the mastery of the brain over the organism is particularly emphasized; but everything that might prove an independence of the psychic life from the demonstrable organic changes, or a spontaneity in its manifestations, is alarming to the psychiatrist nowadays, as if an acknowledgment of the same were bound to bring back the times of natural philosophy and the metaphysical conception of the psychic essence.

(d) Why the Dream is Forgotten after Awakening

That the dream "fades away" in the morning is proverbial. To be sure, it is capable of recollection. For we know the dream only by recalling it after awakening; but very often we believe that we remember it only incompletely, and that during the night there was more of it; we can observe how the memory of a dream which has been still vivid in the morning vanishes in the course of the day, leaving only a few small fragments; we often know that we have been dreaming, but we do not know what; and we are so well used to the fact that the dream is liable to be forgotten that we do not reject as absurd the possibility that one may have been dreaming even when one knows nothing in the morning of either the contents or the fact of dreaming. On the other hand, it happens that dreams manifest an extraordinary retentiveness in the memory. I have had occasion to analyse with my patients dreams which had occurred to them twenty-five years or more previously, and I can remember a dream of my own which is separated from the present day by at least thirty-seven years, and yet has lost nothing of its freshness in my memory.

The forgetting of dreams is treated in the most detailed manner by Strümpell.⁶⁶ This forgetting is evidently a complex phenomenon; for Strümpell does not explain it by a single reason, but by a considerable number of reasons.

In the first place, all those factors which produce forgetfulness in the waking state are also determinant for the forgetting of dreams. When awake we are wont soon to forget a large number of sensations and perceptions because they are too feeble, and because they are connected with a slight amount of emotional feeling. This is also the case with many dream pictures; they are forgotten because they are too weak, while stronger pictures in proximity will be remembered. Moreover, the factor of intensity in itself is not the only determinant for the preservation of the dream pictures; Strümpell, as well as other authors (Calkins), admits that dream pictures are often rapidly forgotten, although they are known to have been vivid, whereas among those that are retained in memory there are many that are very shadowy and hazy. Besides, in the waking state one is wont to forget easily what happened only once, and to note more easily things of repeated occurrence. But most dream pictures are single experiences,^J and this peculiarity equally contributes towards the forgetting of all dreams. Of greater significance is a third motive for forgetting. In order that feelings, presentations, thoughts and the like, should attain a certain degree of memory, it is important that they should not remain isolated, but that they should enter into connections and associations of a suitable kind. If the words of a short verse are taken and mixed together, it will be very difficult to remember them. Now dreams in most cases lack sense and order. Dream compositions are by their very nature incapable of being remembered, and they are forgotten because they usually crumble together the very next moment. To be sure, these conclusions are not in full accord with the observation of Radestock⁵⁴ (p. 168), that we retain best just those dreams which are most peculiar.

According to Strümpell, there are still other factors effective in the forgetting of dreams which are derived from the relation of the dream to the waking state. The forgetfulness of the waking consciousness for dreams is evidently only the counterpart of the fact already mentioned, that the dream (almost) never takes over successive memories from the waking state, but only certain details of these memories which it tears away from the habitual psychic connections in which they are recalled while we are awake. The dream composition, therefore, has no place in the company of psychic successions which fill the mind. It lacks all the aids of memory. "In this manner the dream structure rises, as it were, from the soil of our psychic life, and floats in psychic space like a cloud in the sky, which the next breath of air soon dispels" (p. 87). This is also aided by the fact that, upon awakening, the attention is immediately seized by the inrushing sensory world, and only very few dream pictures can withstand this power.

As a last factor favouring the forgetting of dreams, we may mention the fact that most people generally take little interest in their dreams. One who investigates dreams for a time, and takes a special interest in them, usually dreams more during that time than at any other; that is, he remembers his dreams more easily and more frequently.

Two other reasons for the forgetting of dreams added by Bonatelli (given by Benini³) to those of Strümpell have already been included in the latter; namely, (1) that the change of the general feeling between the sleeping and waking states is unfavourable to the mutual reproductions, and (2) that the different arrangement of the presentation material in the dream makes the dream untranslatable, so to speak, for the waking consciousness.

It is the more remarkable, as Strümpell observes, that, in spite of all these reasons for forgetting the dream, so many dreams are retained in memory. Certain peculiarities relating to the memory of dreams have been particularly noticed of late, e.g., that a dream which is considered forgotten in the morning may be recalled in the course of the day through a perception which accidentally touches the forgotten content of the dream (Radestock,⁵⁴ Tissié⁶⁸).

Such doubts relating to the exactness of the reproduction of the dream are expressed by Strümpell when he says: "It therefore easily happens that the active consciousness involuntarily inserts much in recollection of the dream; one imagines one has dreamt all sorts of things which the actual dream did not contain."

Jessen³⁶ (p. 547) expresses himself very decidedly: "Moreover we must not lose sight of the fact, hitherto little heeded, that in the investigation and interpretation of orderly and logical dreams we almost always play with the truth when we recall a dream to memory. Unconsciously and unwittingly we fill up the gaps and supplement the dream pictures. Rarely, and perhaps never, has a connected dream been as connected as it appears to us in memory. Even the most truth-loving person can hardly relate a dream without exaggerating and embellishing it."

The observations of V. Eggers,²⁰ though surely independently conceived, sound almost like a translation of Jessen's words: "... L'observation des rêves a ses difficultés spéciales et le seul moyen d'éviter toute erreur en pareille matière est de confier au papier sans le moindre retard ce que l'on vient d'éprouver et de remarquer; sinon, l'oubli vient vite ou total ou partiel; l'oubli total est sans gravité; mais l'oubli partiel est perfide; car si l'on se met ensuite à raconter ce que l'on n'a pas oublié, on est exposé à compléter par imagination les fragments incohérents et disjoints fourni par la mémoire...; on devient artiste à son insu, et le récit, périodiquement répété s'impose à la créance de son auteur, qui, de bonne foi, le présente comme un fait authentique, dûment établi selon les bonnes méthodes..."

Similarly Spitta,⁶⁴ who seems to think that it is only in our attempt to reproduce the dream that we put in order the loosely associated dream elements: "To make connection out of disconnection, that is, to add the process of logical connection which is absent in the dream."

(e) The Psychological Peculiarities of Dreams

In the scientific investigation of the dream we start with the assumption that the dream is an occurrence of our own psychic activity; nevertheless the finished dream appears to us as something strange, the authorship of which we are so little forced to recognise that we can just as easily say "a dream appeared to me," as "I have dreamt." Whence this "psychic strangeness" of the dream? According to our discussion of the sources of dreams we may suppose that it does not depend on the material reaching the dream content; because this is for the most part common to the dream life and waking life. One may ask whether in the dream it is not changes in the psychic processes which call forth this impression, and may so put to test a psychological characteristic of the dream.

No one has more strongly emphasized the essential difference between dream and waking life, and utilised this difference for more far-reaching conclusions, than G. Th. Fechner²⁵ in some observations in his Elements of Psychophysic (p. 520, part 11). He believes that "neither the simple depression of conscious psychic life under the main threshold," nor the distraction of attention from the influences of the outer world, suffices to explain the peculiarities of the dream life as compared with the waking life. He rather believes that the scene of dreams is laid elsewhere than in the waking presentation life. "If the scene of the psychophysical activity were the same during the sleeping and the waking states, the dream, in my opinion, could only be a continuation of the waking ideation maintaining itself at a lower degree of intensity, and must moreover share with the latter its material and form. But the state of affairs is quite different."

Other authors have been content to render prominent one or another of the tangible psychological peculiarities of the dream life, and perhaps to take these as a starting point for more far-reaching attempts at explanation.

It has been justly remarked that one of the main peculiarities of the dream life appears even in the state of falling asleep, and is to be designated as the phenomenon inducing sleep. According to Schleiermacher⁶¹ (p. 351), the characteristic part of the waking state is the fact that the psychic activity occurs in ideas rather than in pictures. But the dream thinks in pictures, and one may observe that with the approach of sleep the voluntary activities become difficult in the same measure as the involuntary appear, the latter belonging wholly to the class of pictures.

The 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.

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.^K 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."

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 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 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."^L

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.).

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 suffers 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.

The idea occurs to us that the peculiarities of the dream may be explained through the inferior psychic activity during the sleeping state, but now comes the impression made by the dream upon our waking judgment which is contrary to such a conception. The dream is disconnected, it unites without hesitation the worst contradictions, it allows impossibilities, it disregards our authoritative knowledge from the day, and evinces ethical and moral dulness. He who would behave in the waking state as the dream does in its situations would be considered insane. He who in the waking state would speak in such manner or report such things as occur in the dream content, would impress us as confused and weak-minded.

With unusual unanimity—the exceptions will be dealt with elsewhere—the authors have pronounced their judgments on the dream—such judgments as lead immediately to a definite theory or explanation of the dream life. It is time that I should supplement the résumé which I have just given with a collection of the utterances of different authors—philosophers and physicians—on the psychological character of the dream.

According to Lemoine,⁴² the incoherence of the dream picture is the only essential character of the dream.

Maury⁴⁸ agrees with him; he says (p. 163): "Il n'y a pas des rêves absolument raisonnables et qui ne contiennent quelque incohérence, quelque anachronisme, quelque absurdité."

Dugas¹⁹ says: "Le rêve, c'est l'anarchie psychique, affective et mentale, c'est le jeu des fonctions livrées à elles-mêmes et s'exerçant sans contrôle et sans but; dans le rêve l'esprit est un automate spirituel."

The absurdity of the presentation connections appearing in the dream can hardly be more strongly condemned than it was by Cicero (De Divin. II.): "Nihil tam praepostere, tam incondite, tam monstruose cogitari potest, quod non possimus somniare."

Fechner⁵² says (p. 522): "It is as if the psychological activity were transferred from the brain of a reasonable being into the brain of a fool."

Radestock³⁵ (p. 145) says: "It seems indeed impossible to recognise in this absurd action any firm law. Having withdrawn itself from the strict police of the rational will guiding the waking presentation life, and of the attention, the dream whirls everything about kaleidoscopically in mad play."

Hildebrandt³⁵ (p. 45) says: "What wonderful jumps the dreamer allows himself, e.g., in his chain of reasoning! With what unconcern he sees the most familiar laws of experience turned upside down! What ridiculous contradictions he can tolerate in the orders of nature and society before things go too far, as we say, and the overstraining of the nonsense brings an awakening!"

Binz⁴ (p. 33) points to a dream theory resulting from the impressions. "Among ten dreams nine at least have an absurd content. We unite in them persons or things which do not bear the slightest relation to one another. In the next moment, as in a kaleidoscope, the grouping changes, if possible to one more nonsensical and irrational than before; thus the changing play of the imperfectly sleeping brain continues until we awaken, and put our hand to our forehead and ask ourselves whether we really still possess the faculty of rational imagination and thought."

Maury⁴⁸ (p. 50) finds for the relation of the dream picture to the waking thoughts, a comparison most impressive for the physician: "La production de ces images que chez l'homme éveillé fait le plus souvent naître la volonté, correspond, pour l'intelligence, à ce que cont pour la motilité certains mouvements que nous offrent la chorée et les affections paralytiques..."

According to Strümpell,⁶⁶ some logical mental operations based on relations and connections disappear in the dream—naturally also at points where the nonsense is not obvious (p. 26). According to Spitta,⁶⁴ (p. 148) the presentations in the dream are entirely withdrawn from the laws of causality. Radestock⁵⁴ and others emphasize the weakness of judgment and decision in the dream. According to Jodl³⁷ (p. 123), there is no critique in the dream, and no correcting of a series of perceptions through the content of the sum of consciousness. The contradictions manifested in the dream towards our conscious knowledge are explained by Stricker⁷⁷⁷⁸ (and many others), on the ground that facts are forgotten in the dream and logical relations between presentations are lost (p. 98), &c., &c.

The authors who in general speak thus unfavourably about the psychic capacities in the dream, nevertheless admit that the dream retains a certain remnant of psychic activity. One might inquire as to the kind and behaviour of the remnants of the psychic life which manifest themselves in the dream. It is now quite universally acknowledged that the reproductive capacity, the memory in the dream, seems to have been least affected; indeed it may show a certain superiority over the same function in the waking life (vid. supra, p. 10), although a part of the absurdities of the dream are to be explained by just this forgetfulness of the dream life. According to Spitta,⁶⁴ it is the emotional life of the psyche that is not overtaken by sleep and that then directs the dream.

Scholz⁵⁹ (p. 37) sees a psychic activity manifested in the dream in the "allegorising interpretation" to which the dream material is subjected. Siebeck⁶² verifies also in the dream the "supplementary interpretative activity" (p. 11) which the mind exerts on all that is perceived and viewed. The judgment of the apparently highest psychic function, the consciousness, presents for the dream a special difficulty. As we can know anything only through consciousness, there can be no doubt as to its retention; Spitta, however, believes that only consciousness is retained in the dream, and not self-consciousness. Delbœuf¹⁶ confesses that he is unable to conceive this differentiation.

The laws of association which govern the connection of ideas hold true also for the dream pictures; indeed, their domination evinces itself in a purer and stronger expression in the dream than elsewhere. Strümpell⁶² (p. 70) says: "The dream follows either the laws of undisguised presentations as it seems exclusively or organic stimuli along with such presentations, that is, without being influenced by reflection and reason, æsthetic sense, and moral judgment."

It has been repeatedly observed that the associations which connect the dream presentations with one another are of a particular kind, and different from those found in the waking mental activity. Thus Volkelt⁷² says: "In the dream, the ideas chase and hunt each other on the strength of accidental similarities and barely perceptible connections. All dreams are pervaded by such loose and free associations." Maury⁴⁸ attaches great value to this characteristic of connection between presentations, which allows him to bring the dream life in closer analogy to certain mental disturbances. He recognises two main characters of the délire: "(1) une action spontanée et comme automatique de l'esprit; (2) une association vicieuse et irregulière des idées" (p. 126). Maury gives us two excellent examples from his own dreams, in which the mere similarity of sound forms the connection of the dream presentations. He dreamed once that he undertook a pilgrimage (pélerinage) to Jerusalem or Mecca. After many adventures he was with the chemist Pelletier; the latter after some talk gave him a zinc shovel (pelle) which became his long battle sword in the dream fragment which followed (p. 137).

Without wishing to linger at its apparent absurdity, Havelock Ellis²³ considers the dream as "an archaic world of vast emotions and imperfect thoughts," the study of which may make us acquainted with primitive stages of development of the psychic life. A thinker like Delbœuf¹⁶ asserts—to be sure without adducing proof against the contradictory material, and hence indeed unjustly: "Dans le sommeil, hormis la perception, toutes les facultés de l'esprit, intelligence, imagination, mémoire, volonté, moralité, restant intactes dans leur essence; seulement, elles s'appliquent à des objets imaginaires et mobiles. Le songeur est un acteur qui joue à volonté les fous et les sages, les bourreaux et les victimes, les nains et les géants, les démons et les anges" (p. 222).

The scale of the estimation of the dream as a psychic product has a great range in the literature; it reaches from the lowest under-estimation, the expression of which we have come to know, through the idea of a value not yet revealed to the over-estimation which places the dream far above the capacities of the waking life. Hildebrandt,³⁵ who, as we know, sketches the psychological characteristics into three antinomies, sums up in the third of these contradistinctions the extreme points of this series as follows (p. 19): "It is between a climax, often an involution which raises itself to virtuosity, and on the other hand a decided diminution and weakening of the psychic life often leading below the human niveau."

It is unquestionable that the psychic capacities of the dream have found quicker and warmer recognition in that intellectual period which now lies behind us, when philosophy rather than exact natural science ruled intelligent minds. Utterances like those of Schubert, that the dream frees the mind from the power of outer nature, that it liberates the soul from the chains of the sensual, and similar opinions expressed by the younger Fichte,^M and others, who represent the dream as a soaring up of the psychic life to a higher stage, hardly seem conceivable to us to-day; they are only repeated at present by mystics and devotees. With the advance of the scientific mode of thinking, a reaction took place in the estimation of the dream. It is really the medical authors who are most prone to underrate the psychic activity in the dream, as being insignificant and invaluable, whereas, philosophers and unprofessional observers—amateur psychologists—whose contributions in this realm can surely not be overlooked, in better agreement with the popular ideas, have mostly adhered to the psychic value of the dream.

Among the superior activities which, even on sober comparison, one is tempted to ascribe to the dream life, memory is the most striking; we have fully discussed the frequent experiences which prove this fact. Another superiority of the dream life, frequently extolled by the old authors, viz. that it can regard itself supreme in reference to distance of time and space, can be readily recognised as an illusion. This superiority, as observed by Hildebrandt,³⁵ is only illusional; the dream takes as much heed of time and space as the waking thought, and this because it is only a form of thinking. The dream is supposed to enjoy still another advantage in reference to time; that is, it is independent in still another sense of the passage of time. Dreams like the guillotine dream of Maury,⁴⁸ reported above, seem to show that the dream can crowd together more perception content in a very short space of time than can be controlled by our psychic activity in the waking mind.

That the dream has the ability to take up the intellectual work of the day and bring to a conclusion what has not been settled during the day, that it can solve doubt and problems, and that it may become the source of new inspiration in poets and composers, seems to be indisputable, as is shown by many reports and by the collection compiled by Chabaneix.¹¹ But even if there be no dispute as to the facts, nevertheless their interpretation is open in principle to a great many doubts.

Finally the asserted divinatory power of the dream forms an object of contention in which hard unsurmountable reflection encounters obstinate and continued faith. It is indeed just that we should refrain from denying all that is based on fact in this subject, as there is a possibility that a number of such cases may perhaps be explained on a natural psychological basis.

(f) The Ethical Feelings in the Dream

For reasons which will be understood only after cognisance has been taken of my own investigations of the dream, I have separated from the psychology of the dream the partial problem whether and to what extent the moral dispositions and feelings of the waking life extend into the dreams. The same contradictions which we were surprised to observe in the authors' descriptions of all the other psychic capacities strike us again here. Some affirm decidedly that the dream knows nothing of moral obligations; others as decidedly that the moral nature of man remains even in his dream life.

A reference to our dream experience of every night seems to raise the correctness of the first assertion beyond doubt. Jessen³⁶ says (p. 553): "Nor does one become better or more virtuous in the dream; on the contrary, it seems that conscience is silent in the dream, inasmuch as one feels no compassion and can commit the worst crimes, such as theft, murder, and assassination, with perfect indifference and without subsequent remorse."

Radestock⁵⁴ (p. 146) says: "It is to be noticed that in the dream the associations terminate and the ideas unite without being influenced by reflection and reason, æsthetic taste, and moral judgment; the judgment is extremely weak, and ethical indifference reigns supreme."

Volkelt⁷² (p. 23) expresses himself as follows: "As every one knows, the sexual relationship in the dream is especially unbridled. Just as the dreamer himself is shameless in the extreme, and wholly lacking moral feeling and judgment, so also he sees others, even the most honoured persons, engaged in actions which even in thought he would blush to associate with them in his waking state."

Utterances like those of Schopenhauer, that in the dream every person acts and talks in accordance with his character, form the sharpest contrast to those mentioned above. R. P. Fischer^N maintains that the subjective feelings and desires or affects and passions manifest themselves in the wilfulness of the dream life, and that the moral characteristics of a person are mirrored in his dream.

Haffner³² (p. 25): "With rare exceptions... a virtuous person will be virtuous also in his dreams; he will resist temptation, and show no sympathy for hatred, envy, anger, and all other vices; while the sinful person will, as a rule, also find in his dreams the pictures which he has before him while awake."

Scholz⁵⁹ (p. 36): "In the dream there is truth; despite all masking in pride or humility, we still recognise our own self... The honest man does not commit any dishonourable offence even in the dream, or, if this does occur, he is terrified over it as if over something foreign to his nature."

Pfaff,^O varying a familiar proverb, says: "Tell me for a time your dreams, and I will tell you what you are within."

The short work of Hildebrandt,³⁵ from which I have already taken so many quotations, places the problem of morality in the dream as the central point of its interest. For Hildebrandt, too, it is a strict rule that the purer the life, the purer the dream; the impurer the former, the impurer the latter.

The moral nature of man remains even in the dream: "But while we are not offended nor made suspicious by an arithmetical error no matter how obvious, by a reversal of science no matter how romantic, or by an anachronism no matter how witty, we nevertheless do not lose sight of the difference between good and evil, right and wrong, virtue and vice. No matter how much of what follows us during the day may vanish in our hours of sleep—Kant's categorical imperative sticks to our heels as an inseparable companion from whom we cannot rid ourselves even in slumber..." (p. 45, &c.).

Yielding to the most earnest reflection, Hildebrandt confesses that he is inclined simply to deny all responsibility for faults and dream sins. (P. 52): "No dream thought can be imagined whose first motive has not already moved through the mind while awake as some wish, desire, or impulse." Concerning this original impulse we must say that the dream has not discovered it—it has only imitated and extended it, it has only elaborated a bit of historical material which it has found in us, into dramatic form; it enacts the words of the apostle: He who hates his brother is a murderer. "In this sense, which is difficult to impugn, we understand the words of Christ: Out of the heart come evil thoughts—for we can hardly help being convinced that every sin committed in the dream brings with it at least a vague minimum of guilt."

A clearer light is thrown on the psychological status of this idea of contrast by another observation of Hildebrandt, that the dream at times allows us to glance into the deep and inmost recesses of our being, which are generally closed to us in our waking state (p. 55). Radestock⁵⁴ (p. 84) says that the dream often only reveals to us what we do not wish to admit to ourselves, and that we therefore unjustly condemn it as a liar and deceiver.

If one believes in the capacity of the dream to reveal an actually existing but repressed or concealed immoral disposition of the dreamer, he could not emphasize his opinion more strongly than with the words of Maury (p. 115): "En rêve l'homme se révèle donc tout entier à soi-même dans sa nudité et sa misère natives. Dès qu'il suspend l'exercice de sa volonté, il dévient le jouet de toutes les passions contre lesquelles, à l'état de veille, la conscience, le sentiment d'honneur, la crainte nous défendent." He then mentions as an example that his dreams often show him as a victim of just those superstitions which he most violently combats in his writing.

A passage in the studies on consciousness by Stricker⁷⁷ reads: "The dream does not consist of delusions merely; if, e.g., one is afraid of robbers in the dream, the robbers are, of course, imaginary, but the fear is real."

(g) Dream Theories and Functions of the Dream

A statement concerning the dream which as far as possible attempts to explain from one point of view many of its noted characters, and which at the same time determines the relation of the dream to a more comprehensive sphere of manifestations, may be called a theory of dreams. 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.

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. 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. 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 has still another sense. It is meant to dispute the dignity of a psychic process for the dream. In this sense it becomes something entirely untranslatable, for how could the ten fingers of an unmusical player produce any music? This 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. 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). 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."

Another author, Yves Delage,¹⁵ bases his theory on the same characteristics of the dream, 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 psychic energy accumulated during the day through inhibition or suppression becomes the mainspring of the dream at night. Delage stops here in his train of thought; he can ascribe only the smallest part to an independent psychic activity in the dream.

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. Burdach,⁸ therefore, cites with approval the admirable words in which the poet Novalis lauds the sway of the dream: "The dream is a bulwark against the regularity and commonness of life, a free recreation of the fettered phantasy, in which it mixes together all the pictures of life and interrupts the continued earnestness of grown-up men with a joyous children's play."

The refreshing and curative activity of the dream is even more impressively depicted by Purkinje.⁵³ "The productive dreams in particular would perform these functions. They are easy plays of the imagination, which have no connection with the events of the day. The mind does not wish to continue the tension of the waking life, but to release it and recuperate from it. Many sore spots in the mind, which the day keeps continually open, sleep heals by covering them and guarding against fresh excitement."

The most original attempt to explain the dream as a special activity of the mind was the one undertaken by Scherner⁵⁸ in 1861. In the dream the activity of the mind designated as phantasy, freed from all rational domination and hence completely uncontrolled, rises to absolute supremacy. Clearness of language is rendered especially difficult by the fact that it shows a dislike for expressing an object by its own picture, but prefers a strange picture, if the latter can only express that moment of the object which it wishes to describe. This is the symbolising activity of the phantasy... According to Scherner, the material upon which the dream phantasy exerts its artistic activity is preponderately that of the organic sensory stimuli which are so obscure during the day; hence the phantastic theory of Scherner, and the perhaps over-sober theories of Wundt and other physiologists agree in their assumption of the dream sources and dream excitants.

Indeed Scherner holds the opinion that the dream phantasy has a certain favourite representation for the entire organism; this representation would be the house. "Thus the breathing lungs find their symbol in the flaming stove with its gaseous roaring, the heart in hollow boxes and baskets, the bladder in round, bag-shaped, or simply hollowed objects. In the female sexual dream the tightness of the closely approximated thighs may be symbolised by a narrow courtyard surrounded by houses, and the vagina by a very narrow, slippery and soft footpath, leading through the courtyard, upon which the dreamer is obliged to walk, in order perhaps to carry a letter to a gentleman" (Volkelt, p. 39). It is particularly noteworthy that at the end of such a physically exciting dream, the phantasy, as it were, unmasks by representing the exciting organ or its function unconcealed. Volkelt,⁷² next attempted to penetrate further into the character of this phantasy.

(h) Relations between the Dream and Mental Diseases

When we speak of the relation of the dream to mental disturbances, we may think of three different things: (1) Etiological and clinical relations, as when a dream represents or initiates a psychotic condition. (2) Changes to which the dream life is subjected in mental diseases. (3) Inner relations between the dream and the psychoses, analogies indicating an intimate relationship.

In regard to the clinical and etiological relations between the dream and the psychoses, I will report the following observations as paradigms. Hohnbaum asserts that the first attack of insanity frequently originates in an anxious and terrifying dream. Sante de Sanctis adduces similar observations in paranoiacs, and declares the dream to be, in some of them, the "vraie cause déterminante de la folie." Thomayer⁷⁰ calls attention to anxiety dreams which must be conceived as equivalent to epileptic attacks. Allison has described nocturnal insanity, in which the subjects are apparently perfectly well in the day-time, while hallucinations, fits of frenzy, and the like regularly appear at night. Tissié reports abundant observations from recent times in which actions of a pathological character had their origin in dreams. Guislain describes a case in which sleep was replaced by an intermittent insanity.

In cases of convalescence from insanity, it is often especially obvious that, while the functions of the day are normal, the dream life may still belong to the psychosis. Gregory is said first to have called attention to such cases (cited by Krauss³⁹). Macario (reported by Tissié) gives account of a maniac who, a week after his complete recovery again experienced in dreams the flight of ideas and the passionate impulses of his disease.

Concerning the changes to which the dream life is subjected in chronic psychotic persons, very few investigations have so far been made. On the other hand, timely attention has been called to the inner relationship between the dream and mental disturbance. According to Maury,⁴⁷ Cubanis first called attention to this; following him came Lelut, J. Moreau, and more particularly the philosopher Maine de Biran. Radestock⁵⁴ begins the chapter dealing with this comparison, by giving a collection of expressions showing the analogy between the dream and insanity. Kant somewhere says: "The lunatic is a dreamer in the waking state." Schopenhauer terms the dream a short insanity, and insanity a long dream. Wundt, in the Physiological Psychology, declares: "As a matter of fact we may in the dream ourselves live through almost all symptoms which we meet in the insane asylums."

The specific agreements are enumerated by Spitta.⁶⁴ And indeed, very similarly, by Maury in the following grouping: "(1) Suspension or at least retardation, of self-consciousness. (2) Modified perception of the sensory organs. (3) Combination of ideas with each other exclusively in accordance with the laws of association and of reproduction, hence automatic formation of groups. (4) Changing or transformation of the personality."

The above passage from Radestock, an abstract of a keen discussion of Griesinger³¹ (p. 111), reveals with the greatest clearness the wish fulfilment as a characteristic of the imagination, common to the dream and the psychosis. "Absurd combinations of ideas and weakness of judgment are the main characteristics of the dream and of insanity." Both are devoid of any measure of time. The dissociation of personality in the dream fully corresponds to the well-known splitting of personality in hallucinatory paranoia; the dreamer, too, hears his own thoughts expressed by strange voices.

Considering all this, it is not surprising that Radestock condenses his own opinion and that of many others into the following: "Insanity, an abnormal phenomenon of disease, is to be regarded as an enhancement of the periodically recurring normal dream states" (p. 228). Krauss³⁹ attempted to base the relationship between the dream and insanity upon the etiology. According to him, the fundamental element common to both is the organically determined sensation, the sensation of physical stimuli, the general feeling produced by contributions from all the organs.

The volumnious book on the dream by Sante de Sanctis, of which a German translation appeared soon after its publication, has, so to speak, crossed with mine. A younger philosopher, H. Swoboda,^P who has undertaken to extend W. Fliesse's discovery of biological periodicity (in groups of twenty-three and twenty-eight days) to the psychic field, has produced an imaginative work, in which, among other things, he has used this key to solve the riddle of the dream. The interpretation of dreams would herein have fared badly; the material contained in dreams would be explained through the coincidence of all those memories which during the night complete one of the biological periods for the first or the n-th time.