power of subjective sensory excitements is offered by the so-called hypnogogic hallucinations, which have been described by John Müller as "phantastic visual manifestations." They are those very vivid and changeable pictures which occur regularly in many people during the period of falling asleep, and which may remain for awhile even after the eyes have been opened. Maury,48 who was considerably troubled by them, subjected them to a thorough study, and maintained that they are related to or rather identical with dream pictures—this has already been asserted by John Müller. Maury states that a certain psychic passivity is necessary for their origin; it requires a relaxation of the tension of attention (p. 59). But in any ordinary disposition a hypnogogic hallucination may be produced by merging for a second into such lethargy, after which one perhaps awakens until this oft-repeated process terminates in sleep. According to Maury, if one awakens shortly thereafter, it is often possible to demonstrate the same pictures in the dream which one has perceived as hypnogogic hallucinations before falling asleep (p. 134). Thus it once happened to Maury with a group of pictures of grotesque figures, with distorted features and strange headdresses, which obtruded themselves upon him with incredible importunity during the period of falling asleep, and which he recalled having dreamed upon awakening. On another occasion, while suffering from hunger, because he kept himself on a rather strict diet, he saw hypnogogically a plate and a hand armed with a fork taking some food from the plate. In his dream he found himself at a table abundantly supplied with food, and heard the rattle made by the diners with their forks. On still another occasion, after falling asleep with irritated and painful eyes, he had the hypnogogic hallucination of seeing microscopically small characters which he was forced to decipher one by one with great exertion; having been awakened from his sleep an hour later, he recalled a dream in which there was an open book with very small letters, which he was obliged to read through with laborious effort.
Just as in the case of these pictures, auditory hallucinations of words, names, &c., may also appear hypnogogically, and then repeat themselves in the dream, like an overture announcing the principal motive of the opera which is to follow.
A more recent observer of hypnogogic hallucinations, G. Trumbull Ladd,40 takes the same path pursued by John Müller and Maury. By dint of practice he succeeded in acquiring the faculty of suddenly arousing himself, without opening his eyes, two to five minutes after having gradually fallen asleep, which gave him opportunity to compare the sensations of the retina just vanishing with the dream pictures remaining in his memory. He assures us that an intimate relation between the two can always be recognised, in the sense that the luminous dots and lines of the 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
