that is not for us the most instructive point of this experiment.

If the observer is asked what are the letters that he is sure of having seen, these may be, of course, the letters really written, but there may be also absent letters, either letters that we replaced by others or that have simply been omitted. Thus an observer will see quite distinctly in full light a letter which does not exist, if this letter, on account of the general sense, ought to enter into the phrase. The characters which have really affected the eye have been utilized only to serve as an indication to the unconscious memory of the observer. This memory, discovering the appropriate remembrance, i.e., finding the formula to which these characters give a start toward realization, projects the remembrance externally in an hallucinatory form. It is this remembrance, and not the words themselves, that the observer has seen. It is thus demonstrated that rapid reading is in great part a work of divination, but not of abstract divination. It is an externalization of memories which take advantage, to a certain extent, of the partial realization that they find here and there in order to completely realize themselves.

Thus, in the waking state and in the knowledge that we get of the real objects which surround us, an operation is continually going on which is of quite the same nature as that of the dream. We perceive merely a sketch of the object. This sketch appeals to the complete memory, and this complete memory, which by itself was either unconscious or simply in the thought state, profits by the occasion to come out. It is this kind of hallucination, inserted and fitted into a real frame, that we perceive. It is a shorter process: it is very much quicker done than to see the thing itself. Besides, there are many interesting observations to be made upon the conduct and attitude of the memory images during this operation. It is not necessary to suppose that they are in our memory in a state of inert impressions. They are like the steam in a boiler, under more or less tension.

At the moment when the perceived sketch calls them forth, it is as if they were then grouped in families according to their relationship and resemblances. There are experiments of Münsterberg, earlier than those of Goldscheider and Müller, which appear to me to confirm this hypothesis, although they were made for a very different purpose. Münsterberg wrote the words correctly; they were, besides, not common phrases; they were isolated words taken by chance. Here again the word was exposed during the time too short for it to be entirely perceived. Now, while the observer was looking at the written word, some one spoke in his ear another word of a very different significance. This is what happened: the observer declared that he had seen a word which was not the written word, but which resembled it in its general form, and which besides recalled, by its meaning, the word which was spoken in his ear. For example, the word written was "tumult" and the word spoken was "railroad." The observer read "tunnel." The written word was "Trieste" and the spoken word was the German "Verzweiflung" (despair). The observer read "Trost," which signifies "consolation." It is as if the word "railroad," pronounced in the ear, wakened, without our knowing it, hopes of conscious realization in a crowd of memories which have some relationship with the idea of "railroad" (car, rail, trip, etc.). But this is only a hope, and the memory which succeeds in coming into consciousness is that which the actually present sensation had already begun to realize.

Such is the mechanism of true perception, and such is that of the dream. In both cases there are, on one hand, real impressions made upon the organs of sense, and upon the other memories which encase themselves in the impression and profit by its vitality to return again to life.

But, then, what is the essential difference between perceiving and dreaming? What is sleep? I do not ask, of course, how sleep can be explained physiologically. That is a special question, and besides is far from being settled. I ask what is sleep psychologically; for our mind continues to exercise itself when we are asleep, and it exercises itself as we have just seen on elements analogous to those of waking, on sensations and memories; and also in an analogous manner combines them. Nevertheless we have on the one hand normal perception, and on the other the dream. What is the difference, I repeat? What are the psychological characteristics of the sleeping state?

We must distrust theories. There are a great many of them on this point. Some say that sleep consists in isolating oneself from the external world, in closing the senses to outside things. But we have shown that our senses continue to act during sleep, that they provide us with the outline, or at least the point of departure, of most of our dreams. Some say: "To go to sleep is to stop the action of the superior faculties of the mind," and they talk of a kind of momentary paralysis of the higher centers. I do not think that this is much more exact. In a dream we become no doubt indifferent to logic, but not incapable of logic. There are dreams when we reason with correctness and even with subtlety. I might almost say, at the risk of seeming paradoxical, that the mistake of the dreamer is often in reasoning too much. He would avoid the absurdity if he would remain a simple spectator of the procession of images which compose his dream. But when he strongly desires to explain it, his explanation, intended to bind together incoherent images, can be nothing more than a bizarre reasoning which verges upon absurdity. I recognize, indeed, that our superior intellectual faculties are relaxed in sleep, that generally the logic of a dreamer is feeble enough and often resembles a mere parody of logic. But one might say as much of all of our faculties during sleep. It is then not by the abolition of reasoning, any more than by the closing of the senses, that we characterize dreaming.

Something else is essential. We need something more than theories. We need an intimate contact with the facts. One must make the decisive experiment upon oneself. It is necessary that on coming out of a dream, since we cannot analyze ourselves in the dream itself, we should watch the transition from sleeping to waking, follow upon the transition as closely as possible, and try to express by words what we experience in this passage. This is very difficult, but may be accomplished by forcing the attention. Permit, then, the writer to take an example from his own personal experience, and to tell of a recent dream as well as what was accomplished on coming out of the dream.

Now the dreamer dreamed that he was speaking before an assembly, that he was making a political speech before a political assembly. Then in the midst of the auditorium a murmur rose. The murmur augmented; it became a muttering. Then it became a roar, a frightful tumult, and finally there resounded from all parts timed to a uniform rhythm the cries, "Out! Out!" At that moment he wakened. A dog was baying in a neighboring garden, and with each one of his "Wow-wows" one of the cries of "Out! Out!" seemed to be identical. Well, here was the infinitesimal moment which it is necessary to seize.

The waking ego, just reappearing, should turn to the dreaming ego, which is still there, and, during some instants at least, hold it without letting it go. "I have caught you at it! You thought it was a crowd shouting and it was a dog barking. Now, I shall not let go of you until you tell me just what you were doing!" To