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?