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.