Let us, for the present, give up the idea of finding the meaning of the dream and try instead to clear a path to a better understanding of the dream by means of the elements common to all dreams. From the relation of dreams to the sleeping condition, we concluded that the dream is the reaction to a sleep-disturbing stimulus. As we have heard, this is the only point upon which exact experimental psychology can come to our assistance; it gives us the information that stimuli applied during sleep appear in the dream. There have been many such investigations carried out, including that of the above mentioned Mourly Vold. Indeed, each of us must at some time have been in a position to confirm this conclusion by means of occasional personal observations. I shall choose certain older experiments for presentation. Maury had such experiments made on his own person. He was allowed to smell cologne while dreaming. He dreamed that he was in Cairo in the shop of Johann Marina Farina, and therewith were linked further extravagant adventures. Or, he was slightly pinched in the nape of the neck; he dreamed of having a mustard plaster applied, and of a doctor who had treated him in childhood. Or, a drop of water was poured on his forehead. He was then in Italy, perspired profusely, and drank the white wine of Orvieto.
What strikes us about these experimentally induced dreams we may perhaps be able to comprehend still more clearly in another series of stimulated dreams. Three dreams have been recounted by a witty observer, Hildebrand, all of them reactions to the sound of the alarm clock:
“I go walking one spring morning and saunter through the green fields to a neighboring village. There I see the inhabitants in gala attire, their hymn books under their arms, going church-ward in great numbers. To be sure, this is Sunday, and the early morning service will soon begin. I decide to attend, but since I am somewhat overheated, decide to cool off in the cemetery surrounding the church. While I am there reading several inscriptions, I hear the bell ringer ascend the tower, and now see the little village church bell which is to give the signal for the beginning of the service. The bell hangs a good bit longer, then it begins to swing, and suddenly its strokes sound clear and penetrating, so clear and penetrating that they make an end of — my sleep. The bell-strokes, however, come from my alarm clock.
“A second combination. It is a clear winter day. The streets are piled high with snow. I agree to go on a sleighing party, but must wait a long time before the announcement comes that the sleigh is at the door. Then follow the preparations for getting in-the fur coat is put on, the footwarmer dragged forth — and finally I am seated in my place. But the departure is still delayed until the reins give the waiting horses the tangible signal. Now they pull; the vigorously shaken bells begin their familiar Janizary music so powerfully that instantly the spider web of the dream is torn. Again it is nothing but the shrill tone of the alarm clock.
“And still a third example. I see a kitchen maid walking along the corridor to the dining room with some dozens of plates piled high. The pillar of porcelain in her arms seems to me in danger of losing its balance. ‘Take care!’ I warn her. ‘The whole load will fall to the ground.’ Naturally, the inevitable retort follows: one is used to that, etc., and I still continue to follow the passing figure with apprehensive glances. Sure enough, at the threshold she stumbles — the brittle dishes fall and rattle and crash over the floor in a thousand pieces. But — the endless racket is not, as I soon notice, a real rattling, but really a ringing and with this ringing, as the awakened subject now realizes, the alarm has performed its duty.”
These dreams are very pretty, quite meaningful, not at all incoherent, as dreams usually are. We will not object to them on that score. That which is common to them all is that the situation terminates each time in a noise, which one recognizes upon waking up as the sound of the alarm. Thus we see here how a dream originates, but also discover something else. The dream does not recognize the alarm — indeed the alarm does not appear in the dream — the dream replaces the alarm sound with another, it interprets the stimulus which interrupts the sleep, but interprets it each time in a different way. Why? There is no answer to this question, it seems to be something arbitrary. But to understand the dream means to be able to say why it has chosen just this sound and no other for the interpretation of the alarm-clock stimulus. In quite analogous fashion, we must raise the objection to the Maury experiment that we see well enough that the stimulus appears in the dream, but that we do not discover why it appears in just this form; and that the form taken by the dream does not seem to follow from the nature of the sleep-disturbing stimulus. Moreover, in the Maury experiments a mass of other dream material links itself to the direct stimulus product; as, for example, the extravagant adventures in the cologne dream, for which one can give no account.
Now I shall ask you to consider the fact that the waking dreams offer by far the best chances for determining the influence of external sleep-disturbing stimuli. In most of the other cases it will be more difficult. One does not wake up in all dreams, and in the morning, when one remembers the dream of the night, how can one discover the disturbing stimulus which was perhaps in operation at night? I did succeed once in subsequently establishing such a sound stimulus, though naturally only in consequence of special circumstances. I woke up one morning in a place in the Tyrolese Mountains, with the certainty that I had dreamt the Pope had died. I could not explain the dream, but then my wife asked me: “Did you hear the terrible bell ringing that broke out early this morning from all the churches and chapels?” No, I had heard nothing, my sleep is a sound one, but thanks to this information I understood my dream. How often may such stimuli incite the sleeper to dream without his knowing of them afterward? Perhaps often, perhaps infrequently; when the stimulus can no longer be traced, one cannot be convinced of its existence. Even without this fact we have given up evaluating the sleep disturbing stimuli, since we know that they can explain only a little bit of the dream, and not the whole dream reaction.
But we need not give up this whole theory for that reason. In fact, it can be extended. It is clearly immaterial through what cause the sleep was disturbed and the psyche incited to dream. If the sensory stimulus is not always externally induced, it may be instead a stimulus proceeding from the internal organs, a so-called somatic stimulus. This conjecture is obvious, and it corresponds to the most popular conception of the origin of dreams. Dreams come from the stomach, one often hears it said. Unfortunately it may be assumed here again that the cases are frequent in which the somatic stimulus which operated during the night can no longer be traced after waking, and has thus become unverifiable. But let us not overlook the fact that many recognized experiences testify to the derivation of dreams from the somatic stimulus. It is in general indubitable that the condition of the internal organs can influence the dream. The relation of many a dream content to a distention of the bladder or to an excited condition of the genital organs, is so clear that it cannot be mistaken. From these transparent cases one can proceed to others in which, from the content of the dream, at least a justifiable conjecture may be made that such somatic stimuli have been operative, inasmuch as there is something in this content which may be conceived as elaboration, representation, interpretation of the stimuli. The dream investigator Schirmer (1861) insisted with particular emphasis on the derivation of the dream from organic stimuli, and cited several splendid examples in proof. For example, in a dream he sees “two rows of beautiful boys with blonde hair and delicate complexions stand opposite each other in preparation for a fight, fall upon each other, seize each other, take up the old position again, and repeat the whole performance;” here the interpretation of these rows of boys as teeth is plausible in itself, and it seems to become convincing when after this scene the dreamer “pulls a long tooth out of his jaws.” The interpretation of “long, narrow, winding corridors” as intestinal stimuli, seems sound and confirms Schirmer’s assertion that the dream above all seeks to represent the stimulus-producing organ by means of objects resembling it.
Thus we must be prepared to admit that the internal stimuli may play the same role in the dream as the external.