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 that your feet are not touching the earth. And, nevertheless, not believing yourself asleep, you have lost sight of the fact that you are lying down. Therefore, since you are not lying down and yet your feet do not feel the resistance of the ground, the conclusion is natural that you are floating in space. Notice this also: when levitation accompanies the flight, it is on one side only that you make an effort to fly. And if you woke at that moment you would find that this side is the one on which you are lying, and that the sensation of effort for flight coincides with the real sensation given you by the pressure of your body against the bed. This sensation of pressure, dissociated from its cause, becomes a pure and simple sensation of effort and, joined to the illusion of floating in space, is sufficient to produce the dream.