With this relaxation of the _Will_, and consequently of “attention,”—which is an effort of the Will—ideas begin to flow unbidden into the mind. At first they are banished almost as soon as they appear. But presently they return and disturb the train of waking thought; then they mingle with it; then they put it altogether to rout, and usurp its place. At the beginning, we are competent to sever the intruding ideas from the true ones and we make an effort to banish them if we desire to be wakeful. But they return ever more vividly and persistently, until at length they take possession of the mind. If we are courting sleep, we welcome the intruders and willingly resign the control of our thoughts. In either case the state of actual sleep occurs at the instant when the _Will_ ceases to work and _attention_ ends. Then begins the condition of _Dream_, to be treated of presently. Our business now is to trace, so far as we can, the _mental_ change that attends the condition of sleep. The phenomena just described are the action of the mind in the process of _falling asleep_. The _state of sleep_ presents other features. The mental condition of sleep, apart from dream, is very remarkable and should be carefully noted and remembered by the Student of Psychology. The _Senses_ are suspended—but not entirely. They are rather dulled than paralysed. We hear, but imperfectly, and we are unable to measure the sound. Often a loud noise is not heard when a whisper wakens; or a slight sound seems to the sleeper like the report of cannon. The sense of touch is only dulled, as we know by the manner in which it influences dream. Whether the sense of sight ceases entirely we cannot know, because the eyelids veil the eyes and external impressions are consequently not made upon them. Taste and smell are dimmed but not effaced. CHAPTER IV. THE SEAT OF SLEEP. These facts point to the conclusion that the partial paralysis to which the senses are subjected in sleep does not occur at the points of communication with the external world, but somewhere between the extremity of the sense-nerves and the brain, or at the point of communication between the brain and the Conscious Self. There can be little doubt that impressions are made upon the nerves in sleep as when we are awake. There is some evidence that the impressions so made are conveyed by the afferent nerve to the ganglion at the base of the brain hemispheres. The experiments of Professor FERRIER have proved this ganglion to be the centre upon which the sense-nerves converge; that to this centre those impressions are conveyed and thence are transmitted to the brain hemispheres, or at this point the hemispheres of the intelligence receive notice of their presence.