Are there still further traits in common? I find none, and see only differences everywhere, differences indeed in the apparent length as well as the definiteness of the activities, participation of effects, durability, etc. All this really is not what we might expect of a compulsion-driven, irresistible, convulsive defense against a stimulus. As concerns the dimensions of dreams, there are very short ones which contain only one picture or a few, one thought – yes, even one word only – , others which are uncommonly rich in content, seem to dramatize whole novels and to last very long. There are dreams which are as plain as an experience itself, so plain that we do not recognize them as dreams for a long time after waking; others which are indescribably weak, shadowy and vague; indeed in one and the same dream, the overemphasized and the scarcely comprehensible, indefinite parts may alternate with each other. Dreams may be quite meaningful or at least coherent, yes, even witty, fantastically beautiful. Others, again, are confused, as if feeble-minded, absurd, often actually mad. There are dreams which leave us quite cold, others in which all the effects come to expression – pain deep enough for tears, fear strong enough to waken us, astonishment, delight, etc. Dreams are generally quickly forgotten upon waking, or they may hold over a day to such an extent as to be faintly and incompletely remembered in the evening. Others, for example, the dreams of childhood, are so well preserved that they stay in the memory thirty years later, like fresh experiences. Dreams, like individuals, may appear a single time, and never again, or they may repeat themselves unchanged in the same person, or with small variations. In short, this nightly psychic activity can avail itself of an enormous repertoire, can indeed compass everything which the psychic accomplishes by day, but yet the two are not the same.

One might try to give an account of this many-sidedness of the dream by assuming that it corresponds to different intermediate stages between sleeping and waking, different degrees of incomplete sleep. Yes, but in that case as the psyche nears the waking state, the conviction that it is a dream ought to increase along with the value, content and distinctiveness of the dream product, and it would not happen that immediately beside a distinct and sensible dream fragment a senseless and indistinct one would occur, to be followed again by a goodly piece of work. Surely the psyche could not change its degree of somnolence so quickly. This explanation thus avails us nothing; at any rate, it cannot be accepted offhand.

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. Unfortunately, their evaluation is subject to the same difficulties as those we have already encountered. In a large number of cases the interpretation of the stimuli as somatic remains uncertain and undemonstrable. Not all dreams, but only a certain portion of them, arouse the suspicion that an internal organic stimulus was concerned in their causation. And finally, the internal stimuli will be as little able as the external sensory stimuli to explain any more of the dream than pertains to the direct reaction to the stimuli. The origin, therefore, of the rest of the dream remains obscure.

Let us, however, notice a peculiarity of dream life which becomes apparent in the study of these effects of stimuli. The dream does not simply reproduce the stimulus, but it elaborates it, it plays upon it, places it in a sequence of relationships, replaces it with something else. That is a side of dream activity which must interest us because it may lead us closer to the nature of the dream. If one does something under stimulation, then this stimulation need not exhaust the act. Shakespeare's Macbeth, for example, is a drama created on the occasion of the coronation of the King who for the first time wore upon his head the crown symbolizing the union of three countries. But does this historical occasion cover the content of the drama, does it explain its greatness and its riddle? Perhaps the external and internal stimuli, acting upon the sleeper, are only the incitors of the dream, of whose nature nothing is betrayed to us from our knowledge of that fact.

The other element common to dreams, their psychic peculiarity, is on the one hand hard to comprehend, and on the other hand offers no point for further investigation. In dreams we perceive a thing for the most part in visual forms. Can the stimuli furnish a solution for this fact? Is it actually the stimulus which we experience? Why, then, is the experience visual when optic stimulation incited the dream only in the rarest cases? Or can it be proved, when we dream speeches, that during sleep a conversation or sounds resembling it reached our ear? This possibility I venture decisively to reject.

If, from the common elements of dreams, we get no further, then let us see what we can do with their differences. Dreams are often senseless, blurred, absurd; but there are some that are meaningful, sober, sensible. Let us see if the latter, the sensible dreams, can give some information concerning the senseless ones. I will give you the most recent sensible dream which was told me, the dream of a young man: "I was promenading in Kärtner Street, met Mr. X. there, whom I accompanied for a bit, and then I went to a restaurant. Two ladies and a gentleman seated themselves at my table. I was annoyed at this at first, and would not look at them. Then I did look, and found that they were quite pretty." The dreamer adds that the evening before the dream he had really been in Kärtner Street, which is his usual route, and that he had met Mr. X. there. The other portion of the dream is no direct reminiscence, but bears a certain resemblance to a previous experience. Or another meaningful dream, that of a lady. "Her husband asks, 'Doesn't the piano need tuning?' She: 'It is not worth while; it has to be newly lined.'" This dream reproduces without much alteration a conversation which took place the day before between herself and her husband. What can we learn from these two sober dreams? Nothing but that you find them to be reproductions of daily life or ideas connected therewith. This would at least be something if it could be stated of all dreams. There is no question, however, that this applies to only a minority of dreams. In most dreams there is no sign of any connection with the previous day, and no light is thereby cast on the senseless and absurd dream. We know only that we have struck a new problem. We wish to know not only what it is that the dream says, but when, as in our examples, the dream speaks plainly, we also wish to know why and wherefore this recent experience is repeated in the dream.

I believe you are as tired as I am of continuing attempts like these. We see, after all, that the greatest interest in a problem is inadequate if one does not know a path which will lead to a solution. Up to this point we have not found this path. Experimental psychology gave us nothing but a few very valuable pieces of information concerning the meaning of stimuli as dream incitors. We need expect nothing from philosophy except that lately it has taken haughtily to pointing out to us the intellectual inferiority of our object. Let us not apply to the occult sciences for help. History and popular tradition tell us that the dream is meaningful and significant; it sees into the future. Yet that is hard to accept and surely not demonstrable. Thus our first efforts end in entire helplessness.

Unexpectedly we get a hint from a quarter toward which we have not yet looked. Colloquial usage – which after all is not an accidental thing but the remnant of ancient knowledge, though it should not be made use of without caution – our speech, that is to say, recognizes something which curiously enough it calls "day dreaming." Day dreams are phantasies. They are very common phenomena, again observable in the normal as well as in the sick, and access to their study is open to everyone in his own person. The most conspicuous feature about these phantastic productions is that they have received the name "day dreams," for they share neither of the two common elements of dreams. Their name contradicts the relation to the sleeping condition, and as regards the second common element, one does not experience or hallucinate anything, one only imagines it. One knows that it is a phantasy, that one is not seeing but thinking the thing. These day dreams appear in the period before puberty, often as early as the last years of childhood, continue into the years of maturity, are then either given up or retained through life. The content of these phantasies is dominated by very transparent motives. They are scenes and events in which the egoistic, ambitious and power-seeking desires of the individual find satisfaction. With young men the ambition phantasies generally prevail; in women, the erotic, since they have banked their ambition on success in love. But often enough the erotic desire appears in the background with men too; all the heroic deeds and incidents are after all meant only to win the admiration and favor of women. Otherwise these day dreams are very manifold and undergo changing fates. They are either, each in turn, abandoned after a short time and replaced by a new one, or they are retained, spun out into long stories, and adapted to changes in daily circumstances. They move with the time, so to speak, and receive from it a "time mark" which testifies to the influence of the new situation. They are the raw material of poetic production, for out of his day dreams the poet, with certain transformations, disguises and omissions, makes the situations which he puts into his novels, romances and dramas. The hero of the day dreams, however, is always the individual himself, either directly or by means of a transparent identification with another.

Perhaps day dreams bear this name because of the similarity of their relation to reality, in order to indicate that their content is as little to be taken for real as that of dreams. Perhaps, however, this identity of names does nevertheless rest on a characteristic of the dream which is still unknown to us, perhaps even one of those characteristics which we are seeking. It is possible, on the other hand, that we are wrong in trying to read a meaning into this similarity of designation. Yet that can only be cleared up later.