in deep sleep, at least a functional break in the relation established in the nervous system between stimulation and motor reaction. So that dreams would always be the state of a mind of which the attention was not fixed by the sensori-motor equilibrium of the body. And it appears more and more probable that this relaxing of tension in the nervous system is due to the poisoning of its elements by products of their normal activity accumulated in the waking state. Now, in every way dreams imitate insanity. Not only are all the psychological symptoms of madness found in dreams—to such a degree that the comparison of the two states has become a commonplace—but insanity appears also to have its origin in an exhaustion of the brain, which is caused, like normal fatigue, by the accumulation of certain specific poisons in the elements of the nervous system.[1] We know that insanity is often a sequel to infectious diseases, and that, moreover, it is possible to reproduce experimentally, by toxic drugs, all the phenomena of madness.[2] Is it not likely, therefore, that the loss of mental equilibrium in the insane is simply the result of a disturbance of the sensori-motor relations established in the organism? This
