The Interpretation of Dreams by Sigmund Freud
3. Internal (organic) physical stimuli

If we are disposed to look for the sources of dreams not outside but inside the organism, we must remember that almost all our internal organs, which in a state of health hardly remind us of their existence, may, in states of excitation- as we call them- or in disease, become a source of the most painful sensations, and must therefore be put on a par with the external excitants of pain and sensation. Strumpell, for example, gives expression to a long-familiar experience when he declares that "during sleep the psyche becomes far more deeply and broadly conscious of its coporality than in the waking state, and it is compelled to receive and to be influenced by certain stimulating impressions originating in parts of the body, and in alterations of the body, of which it is unconscious in the waking state." Even Aristotle declares it to be quite possible that a dream may draw our attention to incipient morbid conditions which we have not noticed in the waking state (owing to the exaggerated intensity of the impressions experienced in the dream; and some medical authors, who certainly did not believe in the prophetic nature of dreams, have admitted the significance of dreams, at least in so far as the predicting of disease is concerned. [Cf. M. Simon, p. 31, and many earlier writers.] *

* In addition to the diagnostic valuation of dreams (e.g., by Hippocrates) mention must also be made of their therapeutic significance in antiquity.

Among the Greeks there were dream oracles, which were vouchsafed to patients in quest of recovery. The patient betook himself to the temple of Apollo or Aesculapius; there he was subjected to various ceremonies, bathed, rubbed and perfumed. A state of exaltation having been thus induced, he was made to lie down in the temple on the skin of a sacrificial ram. He fell asleep and dreamed of remedies, which he saw in their natural form, or in symbolic images which the priests afterwards interpreted.

For further references concerning the remedial dreams of the Greeks, cf. Lehmann, i, 74; Bouche-Leclerq; Hermann, Gottesd. Altert. d. Gr., SS 41; Privataltert. SS 38, 16; Bottinger in Sprengel's Beitr. z. Gesch. d. Med., ii, p. 163, et seq.; W. Lloyd, Magnetism and Mesmerism in Antiquity, London, 1877; Dollinger, Heidentum und Judentum, p. 130.

Even in our days there seems to be no lack of authenticated examples of such diagnostic achievements on the part of dreams. Thus Tissie cites from Artigues (Essai sur la valeur semeiologique des Reves) the history of a woman of forty-three, who, during several years of apparently perfect health, was troubled with anxiety-dreams, and in whom a medical examination subsequently revealed an incipient affection of the heart, to which she presently succumbed.

Serious derangements of the internal organs clearly excite dreams in quite a number of persons. The frequency of anxiety-dreams in diseases of the heart and lungs has been generally realized; indeed, this function of the dream-life is emphasized by so many writers that I shall here content myself with a reference to the literature of the subject (Radestock, Spitta, Maury, M. Simon, Tissie). Tissie even believes that the diseased organs impress upon the dream-content its characteristic features. The dreams of persons suffering from diseases of the heart are generally very brief, and end in a terrified awakening; death under terrible circumstances almost always find a place in their content. Those suffering from diseases of the lungs dream of suffocation, of being crushed, and of flight, and a great many of them are subject to the familiar nightmare- which, by the way, Borner has succeeded in inducing experimentally by lying on the face and covering the mouth and nostrils. In digestive disturbances the dream contains ideas from the sphere of gustatory enjoyment and disgust. Finally, the influence of sexual excitement on the dream-content is obvious enough in everyone's experience, and provides the strongest confirmation of the whole theory of dream-instigation by organic sensation.

Moreover, if we study the literature of dreams it becomes quite evident that some writers (Maury, Weygandt) have been led to the study of dream- problems by the influence their own pathological state has had on the content of their dreams.

The enlargement of the number of dream-sources by such undeniably established facts is, however, not so important as one might be led to suppose; for dreams are, after all, phenomena which occur in healthy persons- perhaps in all persons, and every night- and a pathological state of the organs is evidently not one of the indispensable conditions. For us, however, the question is not whence particular dreams originate, but rather: what is the exciting cause of ordinary dreams in normal people?

But we have only to go a step farther to find a source of dreams which is more prolific than any of those mentioned above, and which promises indeed to be inexhaustible. If it is established that the bodily organs become, in sickness, an exciting source of dreams, and if we admit that the mind, when diverted during sleep from the outer world, can devote more of its 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 one way or another grow into dream-images, to reach the sleeping mind. What in the waking state we vaguely perceive as a general sensation, perceptible by its quality alone- a sensation to which, in the opinion of physicians, all the organic systems contribute their share- this general sensation would at night attain a greater potency, and, acting through its individual components, would constitute the most prolific as well as the most usual source of dream-representations. We should then have to discover the laws by which organic stimuli are translated into dream- representations.

This theory of the origin of dreams is the one most favoured by all medical writers. The obscurity which conceals the essence of our being- the "moi splanchnique" as Tissie terms it- from our knowledge, and the obscurity of the origin of dreams, correspond so closely that it was inevitable that they should be brought into relation with one another. The theory according to which the organic sensations are responsible for dreams has, moreover, another attraction for the physician, inasmuch as it favours the aetiological union of the dream with mental derangement, both of which reveal so many points of agreement in their manifestations, since changes in the general organic massive sensation and in the stimuli emanating from the internal organs are also considered to have a far-reaching significance as regards the origin of the psychoses. It is therefore not surprising that the organic stimulus theory can be traced to several writers who have propounded this theory independently.

A number of writers have followed the train of thought developed by Schopenhauer in 1851. Our conception of the universe has its origin in the recasting by the intellect of the impressions which reach it from without in the moulds of time, space and causality. During the day the stimuli proceeding from the interior of the organism, from the sympathetic nervous system, exert at most an unconscious influence on our mood. At night, however, when the overwhelming effect of the impressions of the day is no longer operative, the impressions that surge upward from within are able to force themselves on our attention- just as in the night we hear the rippling of the brook that was drowned in the clamour of the day. But how else can the intellect react to these stimuli than by transforming them in accordance with its own function into things which occupy space and time and follow the lines of causality?- and so a dream originates. Thus Scherner, and after him Volkelt, endeavoured to discover the more intimate relations between physical sensations and dream-pictures; but we shall reserve the discussion of this point for our chapter on the theory of dreams.

As a result of a singularly logical analysis, the psychiatrist Krauss referred the origin of dreams, and also of deliria and delusions, to the same element, namely, to organically determined sensations. According to him, there is hardly any part of the organism which might not become the starting-point of a dream or a delusion. Organically determined sensations, he says, "may be divided into two classes: (1) general sensations- those affecting the whole system; (2) specific sensations- those that are immanent in the principal systems of the vegetative organism, and which may in turn be subdivided 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-image from physical sensations is conceived by Krauss as follows: The awakened sensation, in accordance with some law of association, evokes an idea or image bearing some relation to it, and combines with this idea or image, forming an organic structure, towards which, however, the consciousness does not maintain its normal attitude. For it does not bestow any attention on the sensation, but concerns itself entirely with the accompanying ideas; and this explains why the facts of the case have been so long misunderstood (p. 11 ff.). Krauss even gives this process the special name of "transubstantiation of the sensations into dream-images" (p. 24).

The influence of organic physical stimuli on the formation of dreams is today almost universally admitted, but the question as to the nature of the law underlying this relation is answered in various ways, and often obscurely. On the basis of the theory of physical excitation the special task of dream-interpretation is to trace back the content of a dream to the causative organic stimulus, and if we do not accept the rules of interpretation advanced by Scherner, we shall often find ourselves confronted by the awkward fact that the organic source of excitation reveals itself only in the content of the dream.

A certain agreement, however, appears 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 content. Among these are the well- known dreams of falling from a height, of the dropping out of teeth, of flying, and of embarrassment because one is naked or scantily clad. This last type of dream is said to be caused simply by the dreamer's perception, felt in his sleep, that he has thrown off the bedclothes and is uncovered. The dream that one's teeth are dropping out is explained by "dental irritation," which does not, however, of necessity imply a morbid condition of irritability in the teeth. According to Strumpell, the flying dream is the adequate image employed by the mind to interpret the quantum of stimulus emanating from the rising and sinking of the pulmonary lobes when the cutaneous sensation of the thorax has lapsed into insensibility. This latter condition causes the sensation which gives rise to images of hovering in the air. The dream of falling from a height is said to be due to the fact that an arm falls away from the body, or a flexed knee is suddenly extended, after unconsciousness of the sensation of cutaneous pressure has supervened, whereupon this sensation returns to consciousness, and the transition from unconsciousness to consciousness embodies itself psychically as a dream of falling (Strumpell, p. 118). The weakness of these fairly plausible attempts at explanation clearly lies in the fact that without any further elucidation they allow this or that group of organic sensations to disappear from psychic perception, or to obtrude themselves upon it, until the constellation favourable for the explanation has been established. Later on, however, I shall have occasion to return to the subject of typical dreams and their origin.

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

Another rule reads as follows (p. 35): "If, during sleep, an organic apparatus is in a state of activity, stimulation, or disturbance, the dream will present ideas which correspond with the nature of the organic function performed by that apparatus."

Mourly Vold has undertaken to prove the supposed influence of bodily sensation on the production of dreams by experimenting on a single physiological territory. He changed the positions of a sleeper's limbs, and compared the resulting dreams with these changes. He recorded the following results:

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 with the actual 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 with the actual position.

3. The position of one's own limb may in the dream be attributed to another person.

4. One may also dream 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 behaviour of a limb may in the dream incite ideas which bear some relation or other to this limb. Thus, for example, if we are using our fingers we dream of numerals.

Results such as these would lead me to conclude that even the theory of organic stimulation cannot entirely abolish the apparent freedom of the determination of the dream-picture which will be evoked. *

* See below for a further discussion of the two volumes of records of dreams since published by this writer.