470. A large portion of the Life of every Human being is passed in a state of more or less complete suspension of the Animal powers of sense and motion ; the continued maintenance of those powers requiring periodic intervals of repose, winch seem to be employed in the removal of the products of the “waste” of the Nervous and Muscular tissues that is produced by the exercise of them, and in the repair of the deteriorated mechanism by Nutritive regeneration. The degree of this suspension, however, varies so greatly, as to render it inappropriate to include under one category all the states that are intermediate between ordinary profound Sleep and complete Wakefulness. And as, in the preceding Chapter, we have considered the most characteristic of those which may be regarded as modifications of the waking state, so we shall now treat of those of which sleep may be taken as the type. In so doing, it will be convenient to commence with the state of ordinary ‘profound Sleep, which may be denned as one of complete suspension of sensorial activity : the consciousness of the Ego being neither excited by impressions made on the nerves of his external senses and transmitted upwards to his Sensorium, nor by the downward transmission through the nerves of his internal senses of the results of changes taking place in his Cerebrum (§ 100).