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 matters little. It occurs universally and it constitutes—I may say at once—the principal material of which we shape our dreams, "such stuff as dreams are made on."

Thirty or forty years ago, M. Alfred Maury and, about the same time, M. d'Hervey, of St. Denis, had observed that at the moment of falling asleep these colored spots and moving forms consolidate, fix themselves, take on definite outlines, the outlines of the objects and of the persons which people our dreams. But this is an observation to be accepted with caution, since it emanates from psychologists already half asleep. More recently an American psychologist, Professor Ladd, of Yale, has devised a more rigorous method, but of difficult application, because it requires a sort of training. 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. Permit me to cite to you two observations of M. Tissié on this subject:

"B—— Léon dreams that the theater of Alexandria is on fire; the flame lights up the whole place. All of a sudden he finds himself transported to the midst of the fountain in the public square; a line of fire runs along the chains which connect the great posts placed around the margin. Then he finds himself in Paris at the exposition, which is on fire. He takes part in terrible scenes, etc. He wakes with a start; his eyes catch the rays of light projected by the dark lantern which the night nurse flashes toward his bed in passing. M—— Bertrand dreams that he is in the marine infantry where he formerly served. He goes to Fort-de-France, to Toulon, to Loriet, to Crimea, to Constantinople. He sees lightning, he hears thunder, he takes part in a combat in which he sees fire leap from the mouths of cannon. He wakes with a start. Like B., he was wakened by a flash of light projected from the dark lantern of the night nurse." Such are often the dreams provoked by a bright and sudden light.

Very different are those which are suggested by a mild and continuous light like that of the moon. A. Krauss tells how one day on awakening he perceived that he was extending his arm toward what in his dream appeared to him to be the image of a young girl. Little by little this image melted into that of the full moon which darted its rays upon him. It is a curious thing that one might cite other examples of dreams where the rays of the moon, caressing the eyes of the sleeper, evoked before him virginal apparitions. May we not suppose that such might have been the origin in antiquity of the fable of Endymion—Endymion the shepherd, lapped in perpetual slumber, for whom the goddess Selene, that is, the moon, is smitten with love while he sleeps?

I have spoken of visual sensations. They are the principal ones. But the auditory sensations nevertheless play a rôle. 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. The creaking of furniture, the crackling of the fire, the rain beating against the window, the wind playing its chromatic scale in the chimney, such are the sounds which come to the ear of the sleeper and which the dream converts, according to circumstances, into conversation, singing, cries, music, etc. Scissors were struck against the tongs in the ears of Alfred Maury while he slept. Immediately he dreamt that he heard the tocsin and took part in the events of June, 1848. Such observations and experiences are numerous. But let us hasten to say that sounds do not play in our dreams so important a rôle as colors. Our dreams are, above all, visual, and even more visual than we think. To whom has it not happened—as M. Max Simon has remarked—to talk in a dream with a certain person, to dream a whole conversation, and then, all of a sudden, a singular phenomenon strikes the attention of the dreamer. He perceives that he does not speak, that he has not spoken, that his interlocutor has not uttered a single word, that it was a simple exchange of thought between them, a very clear conversation, in which, nevertheless, nothing has been heard. The phenomenon is easily enough explained. It is in general necessary for us to hear sounds in a dream. From nothing we can make nothing. And when we are not provided with sonorous material, a dream would find it hard to manufacture sonority.

There is much more to say about the sensations of touch than about those of hearing, but I must hasten. We could talk for hours about the singular phenomena which result from the confused sensations of touch during sleep. These sensations, mingling with the images which occupy our visual field, modify them or arrange them in their own way. Often in the midst of the night the contact of our body with its light clothing makes itself felt all at once and reminds us that we are lightly clothed. Then, if our dream is at the moment taking us through the street, it is in this simple attire that we present ourselves to the gaze of the passers-by, without their appearing to be astonished by it. We are ourselves astonished in the dream, but that never appears to astonish other people. I cite this dream because it is frequent. There is another which many of us must have experienced. It consists of feeling oneself flying through the air or floating in space. Once having had this dream, one may be quite sure that it will reappear; and every time that it recurs the dreamer reasons in this way: "I have had before now in a dream the illusion of flying or floating, but this time it is the real thing. It has certainly proved to me that we may free ourselves from the law of gravitation." Now, if you wake abruptly from this dream, you can analyze it without difficulty, if you undertake it immediately. You will see that you feel very clearly