The subject which I have to discuss here is so complex, it raises so many questions of all kinds, difficult, obscure, some psychological, others physiological and metaphysical; in order to be treated in a complete manner it requires such a long development, so I shall go at once to the heart of the question. A dream is this: I perceive objects, but there is nothing there. I see people; I seem to speak to them and I hear what they answer, but there is no one there and I have not really spoken. It is just as if real things and real people were there, but on waking all has disappeared. How does this happen?
But, first, is it true that there is nothing there? I mean, is there any sense material presented to our eyes, to our ears, to our touch, etc., during sleep as well as during waking?
Close the eyes and look attentively at what goes on in the field of our vision. Many people questioned on this point would say that nothing goes on, that they see nothing. This is not surprising, for a certain amount of practice is necessary to be able to observe oneself satisfactorily. But just give the requisite amount of attention, and you will distinguish, little by little, many things. First, in general, a black background. Upon this black background occasionally brilliant points which come and go, rising and descending, slowly and sedately. More often, spots of many colors, sometimes very dull, sometimes, with certain people, so brilliant that reality cannot compare with it. These spots spread and shrink, changing form and color, constantly displacing one another. Sometimes the change is slow and gradual; sometimes again it is a whirlwind of vertiginous rapidity. Where does all this come from? The physiologists and the psychologists have studied this play of colors and have given the names “ocular spectra,” “colored spots,” and “phosphenes” to the phenomenon. They explain it either by the slight modifications which occur ceaselessly in the retinal circulation, or by the pressure that the closed lid exerts upon the eyeball, causing a mechanical excitation of the optic nerve. But the explanation of the phenomenon and the name that is given to it is not what is important here. It occurs universally and it constitutes, I believe, the principal material of which we shape our dreams.
The American psychologist Professor Henry Ladd has devised a rigorous method of testing this hypothesis. It consists in acquiring the habit on awakening in the morning of keeping the eyes closed and retaining for some minutes the dream that is fading from the field of vision and soon would doubtless have faded from that of memory. Then one sees the figures and objects of the dream melt away little by little into phosphenes, identifying themselves with the colored spots that the eye really perceives when the lids are closed. One reads, for example, a newspaper; that is the dream. One awakens and there remains of the newspaper, whose definite outlines are erased, only a white spot with black marks here and there; that is the reality. Or our dream takes us upon the open sea—round about us the ocean spreads its waves of yellowish gray with here and there a crown of white foam. On awakening, it is all lost in a great spot, half yellow and half gray, sown with brilliant points. The spot was there, the brilliant points were there. There was really presented to our perceptions, in sleep, a visual dust, and it was this dust which served for the fabrication of our dreams.
Will this alone suffice? Still considering the sensation of sight, we ought to add to these visual sensations which we may call internal all those which continue to come to us from an external source. The eyes, when closed, still distinguish light from shade, and even, to a certain extent, different lights from one another. These sensations of light, emanating from without, are at the bottom of many of our dreams. A candle abruptly lighted in the room will, for example, suggest to the sleeper, if his slumber is not too deep, a dream dominated by the image of fire, the idea of a burning building. Such are often the dreams provoked by a bright and sudden light.
I have spoken of visual sensations. They are the principal ones. But the auditory sensations nevertheless play a role. First, the ear has also its internal sensations, sensations of buzzing, of tinkling, of whistling, difficult to isolate and to perceive while awake, but which are clearly distinguished in sleep. Besides that we continue, when once asleep, to hear external sounds that the dream converts, according to circumstances, into conversation, singing, cries, music, etc. But let us hasten to say that sounds do not play in our dreams so important a role as colors. Our dreams are, above all, visual.