It is a familiar fact that internal sensations also form a frequent basis of dreams. All the internal organs, when disturbed or distended or excited, may induce dreams, and especially that aggravated kind of dreaming which we call nightmare. This fact is so well known that such dreams are usually dismissed without further analysis. It is a mistake, however, so to dismiss them, for it seems probable that it is precisely here that we may find the most instructive field of dream psychology. On account of the profoundly emotional effect of such dreams they are very interesting to study, but this very element of emotion renders them somewhat obscure objects of study. I do not venture to offer with absolute certainty one or two novel suggestions which dream experiences have led me to regard as probable.
Dreams of flying have so often been recorded – from the time of St. Jerome, who mentions that he was subject to them – that they may fairly be considered to constitute one of the commonest forms of dreaming. All my life, it seems to me, I have at intervals had such dreams in which I imagined myself rhythmically bounding into the air and supported on the air. These dreams, in my case at all events, are not generally remembered immediately on awakening (seeming to indicate that they depend on a cause which does not usually come into action at the end of sleep), but they leave behind them a vague but profound sense of belief in their reality and reasonableness.3 Several writers have attempted to explain this familiar phenomenon. Gowers considers that a spontaneous contraction of the stapedius muscle of the ear during sleep causes a sensation of falling. Stanley Hall, who has himself from childhood had dreams of flying, boldly argues that we have here "some faint reminiscent atavistic echo from the primeval sea"; and that such dreams are really survivals – psychic vestigial remains – taking us back to the far past, in which man's ancestors needed no feet to swim or float. Such a theory may accord with the profound conviction of reality that accompanies such dreams, though this may be more simply accounted for, even by mere repetition, as with dreams of the dead; but it is rather a hazardous theory, and it seems to me infinitely more probable that such dreams are a misinterpretation of actual internal sensations.
My own explanation was immediately suggested by the following dream. I dreamed that I was watching a girl acrobat, in appropriate costume, who was rhythmically rising to a great height in the air and then falling, without touching the floor, though each time she approached quite close to it. At last she ceased, exhausted and perspiring, and had to be led away. Her movements were not controlled by mechanism, and apparently I did not regard mechanism as necessary. It was a vivid dream, and I awoke with a distinct sensation of oppression in the chest. In trying to account for this dream, which was not founded on any memory, it occurred to me that probably I had here the key to a great group of dreams. The rhythmic rising and falling of the acrobat was simply the objectivation of the rhythmic rising and falling of my own respiratory muscles under the influence of some slight and unknown physical oppression, and this oppression was further translated into a condition of perspiring exhaustion in the girl, just as it is recorded that a man with heart disease dreamed habitually of sweating and panting horses climbing up hill. We may recall also the curious sensation as of the body being transformed into a vast bellows which is often the last sensation felt before the unconsciousness produced by nitrous oxide gas. When we are lying down there is a real rhythmic rising and falling of the chest and abdomen, centering in the diaphragm, a series of oscillations which at both extremes are only limited by the air. Moreover, in this position we have to recognize that the whole internal organism – the circulatory, nervous, and other systems – are differently balanced from what they are in the upright position, and that a disturbance of internal equilibrium always accompanies falling. Further, it is possible that the misinterpretation is confirmed to sleeping consciousness by sensations from without, by the absence of the tactile pressure produced by boots on the foot, or the contact of the ground with the soles; we are at once conscious of movement and conscious that the soles of the feet are in contact only with the air. Thus in normal sleep the conditions may be said to be always favorable for producing dreams of flying or of floating in the air, and any slight thoracic disturbance, even in healthy persons, arising from lungs, heart, or stomach, and serving to bring these conditions to sleeping consciousness, may determine such a dream.
There is another common class of dreams which, it seems fairly evident to me, must also find their psychological explanation chiefly in the visceral sensations – I mean dreams of murder. Many psychologists have referred with profound concern to the facility and prevalence of murder in dreams, sometimes as a proof of the innate wickedness of human nature made manifest in the unconstraint of sleep, sometimes as evidence of an atavistic return to the modes of feeling of our ancestors, the thin veneer of civilization being removed during sleep. Maudsley and Mme. de Manacéïne, for example, find evidence in such dreams of a return to primitive modes of feeling. It may well be that there is some element of truth in this view, but even if so we still have to account for the production of such dreams. For this we must, in part at least, fall back upon the logical outcome of dream confusions, owing to which, for instance, a lady who has carved a duck at dinner may a few hours later wake up exhausted by the imaginary effort of cutting off her husband's head. But I think we may find evidence that the dream of murder is often a falsely logical deduction from abnormal visceral and especially digestive sensations.
I may illustrate such dreams by the following example: A lady dreamed that her husband called her aside and said: "Now, do not scream or make a fuss; I am going to tell you something. I have to kill a man. It is necessary, to put him out of his agony." He then took her into his study and showed her a young man lying on the floor with a wound in his breast, and covered with blood. "But how will you do it?" she asked. "Never mind," he replied, "leave that to me." He took something up and leaned over the man. She turned aside and heard a horrible gurgling sound. Then all was over. "Now," he said, "we must get rid of the body. I want you to send for So-and-so's cart, and tell him I wish to drive it." The cart came. "You must help me to make the body into a parcel," he said to his wife; "give me plenty of brown paper." They made it into a parcel, and with terrible difficulty and effort the wife assisted her husband to get the body down stairs and lift it into the cart. At every stage, however, she presented to him the difficulties of the situation. But he carelessly answered all objections, said he would take the body up to the moor, among the stones, remove the brown paper, and people would think the murdered man had killed himself. He drove off and soon returned with the empty cart. "What's this blood in my cart?" asked the man to whom it belonged, looking inside. "Oh, that's only paint," replied the husband. But the dreamer had all along been full of apprehension lest the deed should be discovered, and the last thing she could recall, before waking in terror, was looking out of the window at a large crowd which surrounded the house with shouts of "Murder!" and threats.
This tragedy, with its almost Elizabethan air, was built up out of a few commonplace impressions received during the previous day, none of which impressions contained any suggestion of murder. The tragic element appears to have been altogether due to the psychic influences of indigestion arising from a supper of pheasant. To account for our oppression during sleep, sleeping consciousness assumes moral causes which alone appear to it of sufficient gravity to be the adequate cause of the immense emotions we are experiencing. Even in our waking and fully conscious states we are inclined to give the preference to moral over physical causes, quite irrespective of the justice of our preferences; in our sleeping states this tendency is exaggerated, and the reign of purely moral causes is not disturbed by even a suggestion of mere physical causation.
There is certainly no profounder emotional excitement during sleep than that which arises from a disturbed or distended stomach, and is reflected by the pneumogastric to the accelerated heart and the impeded respiration.4 We are thereby thrown into a state of uninhibited emotional agitation, a state of agony and terror such as we rarely or never attain during waking life. Sleeping consciousness, blindfolded and blundering, a prey to these massive waves from below, and fumbling about desperately for some explanation, jumps at the idea that only the attempt to escape some terrible danger or the guilty consciousness of some awful crime can account for this immense emotional uproar. Thus the dream is suffused by a conviction which the continued emotion serves to support. We do not – it seems most simple and reasonable to conclude