_That point is obviously the point at which the Will exercises its power of control over the body._ Thus does this inquiry into the Psychology of Sleep and Dream promise to throw light upon that mysterious part of the mechanism of man. Professor FERRIER has proved that _the Will_ is exercised through the brain hemispheres, which are the organs of the Intelligence. In the waking and normal condition of the structure the Will commands and controls the body. In sleep and other abnormal conditions the Will ceases to command the body. Between the brain hemispheres and the nerves that move the body something seems to be interposed which either paralyses the Will or ceases to transmit its commands. What is that _something_? Anatomically we find two ganglia, one being the centre upon which the nerves of the senses converge. We know, also, that in sleep the senses cease to transmit their impressions, or do so but dimly. The conclusion is, that the seat of sleep is in this ganglion. Because that is slumbering, the commands of the Will cannot be conveyed from the brain to the body, nor can the messages sent by the senses from the body be conveyed to the brain. It is a moot point if the entire of the mechanism of the brain, or parts of it only, and, if so, what parts, fall into the condition of sleep. But, however that may be, there can be little doubt, from the facts stated above, that the ganglion at the base of the brain hemispheres is the seat of sleep. It is certain that the entire of the two brain hemispheres does not always sleep or dream could not be. Whether the ganglion that interposes between the cerebral centre and the body, and whence streams the nerve system, succumbs to sleep we have no certain knowledge. The presumption is that it does not, for the nerves whose office is to sustain the functions of the vital organs do not sleep. Why they need not the rest that is required by other parts of the mechanism we do not know. Rest appears to be necessary for that portion of the mechanism only that is subject to _voluntary action_. Where _the Will_ controls, the repose of sleep is required for all structure subjected to it. Why? Does the nerve system that moves the mechanism of the body sleep? The bonds that link brain and body are relaxed. The Will has ceased to control either of them. The material form is at rest. But it rests only because the power of the controlling Will is paralysed. All _in_voluntary actions continue and with the more regularity and efficiency because they are not subjected to the disturbing influences of the Will. And what is this potent Will? _The Will_ is merely the expression of the Conscious Self—the power which the Conscious Self exercises over the material mechanism of the body and through the body upon the material world without. CHAPTER V. OF DREAM.