lacunæ. It fills them by calling up other memories which, presenting themselves often with the same deformations and the same incoherences as the preceding, demand in their turn a new explanation, and so on indefinitely. But I do not insist upon this point for the moment. It is sufficient for me to say, in order to answer the question which I have propounded, that the formative power of the materials furnished to the dream by the different senses, the power which converts into precise, determined objects the vague and indistinct sensations that the dreamer receives from his eyes, his ears, and the whole surface and interior of his body, is the memory.

Memory! In a waking state we have indeed memories which appear and disappear, occupying our mind in turn. But they are always memories which are closely connected with our present situation, our present occupation, our present action. I recall at this moment the book of M. d'Hervey on dreams; that is because I am discussing the subject of dreams and this act orients in a certain particular direction the activity of my memory. The memories that we evoke while waking, however distant they may at first appear to be from the present action, are always connected with it in some way. What is the rôle of memory in an animal? It is to recall to him, in any circumstance, the advantageous or injurious consequences which have formerly arisen in analogous circumstances, in order to instruct him as to what he ought to do. In man memory is doubtless less the slave of action, but still it sticks to it. Our memories, at any given moment, form a solid whole, a pyramid, so to speak, whose point is inserted precisely into our present action. But behind the memories which are concerned in our occupations and are revealed by means of it, there are others, thousands of others, stored below the scene illuminated by consciousness. Yes, I believe indeed that all our past life is there, preserved even to the most infinitesimal details, and that we forget nothing, and that all that we have felt, perceived, thought, willed, from the first awakening of our consciousness, survives indestructibly. But the memories which are preserved in these obscure depths are there in the state of invisible phantoms. They aspire, perhaps, to the light, but they do not even try to rise to it; they know that it is impossible and that I, as a living and acting being, have something else to do than to occupy myself with them. But suppose that, at a given moment, I become disinterested in the present situation, in the present action—in short, in all which previously has fixed and guided my memory; suppose, in other words, that I am asleep. Then these memories, perceiving that I have taken away the obstacle, have raised the trapdoor which has kept them beneath the floor of consciousness, arise from the depths; they rise, they move, they perform in the night of unconsciousness a great dance macabre. They rush together to the door which has been left ajar. They all want to get through. But they cannot; there are too many of them. From the multitudes which are called, which will be chosen? It is not hard to say. Formerly, when I was awake, the memories which forced their way were those which could involve claims of relationship with the present situation, with what I saw and heard around me. Now it is more vague images which occupy my sight, more indecisive sounds which affect my ear, more indistinct touches which are distributed over the surface of my body, but there are also the more numerous sensations which arise from the deepest parts of the organism. So, then, among the phantom memories which aspire to fill themselves with color, with sonority, in short with materiality, the only ones that succeed are those which can assimilate themselves with the color-dust that we perceive, the external and internal sensations that we catch, etc., and which, besides, respond to the affective tone of our general sensibility.[1] When this union is effected between the memory and the sensation, we have a dream.

In a poetic page of the Enneades, the philosopher Plotinus, interpreter and continuator of Plato, explains to us how men come to life. Nature, he says, sketches the living bodies, but sketches them only. Left to her own forces she can never complete the task. On the other hand, souls inhabit the world of Ideas. Incapable in themselves of acting, not even thinking of action, they float beyond space and beyond time. But, among all the bodies, there are some which specially respond by their form to the aspirations of some particular souls; and among these souls there are those which recognize themselves in some particular body. The body, which does not come altogether viable from the hand of nature, rises toward the soul which might give it complete life; and the soul, looking upon the body and believing that it perceives its own image as in a mirror, and attracted, fascinated by the image, lets itself fall. It falls, and this fall is life. I may compare to these detached souls the memories plunged in the obscurity of the unconscious. On the other hand, our nocturnal sensations resemble these incomplete bodies. The sensation is warm, colored, vibrant and almost living, but vague. The memory is complete, but airy and lifeless. The sensation wishes to find a form on which to mold the vagueness of its contours. The memory would obtain matter to fill it, to ballast it, in short to realize it. They are drawn toward each other; and the phantom memory, incarnated in the sensation which brings to it flesh and blood, becomes a being with a life of its own, a dream.

The birth of a dream is then no mystery. It resembles the birth of all our perceptions. The mechanism of the dream is the same, in general, as that of normal perception. When we perceive a real object, what we actually see—the sensible matter of our perception—is very little in comparison with what our memory adds to it. When you read a book, when you look through your newspaper, do you suppose that all the printed letters really come into your consciousness? In that case the whole day would hardly be long enough for you to read a paper. The truth is that you see in each word and even in each member of a phrase only some letters or even some characteristic marks, just enough to permit you to divine the rest. All of the rest, that you think you see, you really give yourself as an hallucination. There are numerous and decisive experiments which leave no doubt on this point. I will cite only those of Goldscheider and Müller. These experimenters wrote or printed some formulas in common use, "Positively no admission;" "Preface to the fourth edition," etc. But they took care to write the words incorrectly, changing and, above all, omitting letters. These sentences were exposed in a darkened room. The person who served as the subject of the experiment was placed before them and did not know, of course, what had been written. Then the inscription was illuminated by the electric light for a very short time, too short for the observer to be able to perceive really all the letters. They began by determining experimentally the time necessary for seeing one letter of the alphabet. It was then easy to arrange it so that the observer could not perceive more than eight or ten letters, for example, of the thirty or forty letters composing the formula. Usually, however, he read the entire phrase without difficulty. But