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, or, to express it in his own words: "The clearly printed page, which he was reading in the dream, resolved itself into an object which appeared to his waking perception like part of an actual printed sheet looked at through a little hole in a piece of paper, from too great a distance to be made out distinctly." 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 fight penetrating the eye from the lightened room. The shifting and endlessly variable character of the spontaneous luminous excitation of the retina corresponds exactly to the fitful succession of pictures presented to us in our dreams. If we attach any importance to Ladd's observations, we cannot underrate the productiveness of this subjective source of excitation for the dream; for visual pictures apparently form the principal constituent of our dreams. The share furnished from the spheres of the other senses, beside the sense of hearing, is more insignificant and inconstant.
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.
Moreover, as we go through the literature of the dream, it becomes quite obvious that some of the authors (Maury,48 Weygandt75) have been led to the study of dream problems by the influence of their own pathological state on the content of their dreams.
The addition to dream sources from these undoubtedly established facts is, however, not as important as one might be led to suppose; for the dream is a phenomenon which occurs in healthy persons—perhaps in all persons, and every night—and a pathological state of the organs is apparently not one of its indispensable conditions. For us, however, the question is not whence particular dreams originate, but what may be the exciting source for the ordinary dreams of normal persons.
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. It still remains, however, to examine according to what rule the organic sensations become transformed into 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; but we shall reserve the discussion of these attempts for the chapter on the theory of the dream.
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,