Page:Mind (Old Series) Volume 12.djvu/511

 498 H. MAUDSLEY : motor reaction ; it is in reacting to the impressions of it which his senses are adapted to receive that the person frames the forms and substances of an external world frames the world as he experiences and conceives it. When all these motor reactions, both direct and represen- tative, are entirely shut off, when neither they nor the intuitions of them in the supreme centres take place, then consciousness of an external world ceases necessarily. By monotonous continuance of one sort of sensory impression, as, for example, by gazing or listening continuously, a person may notably bring himself into such a state of complete motor quiescence that consciousness becomes vague, con- fused, and even ceases. Let any one who is in a state of bodily comfort lie perfectly still in bed, in a thoroughly unconstrained and easy position, not exerting the least muscular tension, he will not be conscious of the attitude of his limbs and body, not even whether one limb is touching another or not ; he is not only unconscious of attitude, but unconscious of any sensory impression. Every sensory impression implying suitable motor adaptation, it would be impossible without such fit muscular reaction to see an object, to hear a sound, to smell an odour, to feel a touch ; the motor element is an essential part of the perception. The dissociation of the sensory pole of a nerve tract from its motor pole and from every other motor pole would be the abolition of its sensation. It is probable that an infant could never feel if it could not move. Reverie is not thought, but the absence of thought. The rustic who, musing vacantly, seems deep in thought, is not really thinking ; he is pretty nigh unconscious, and there- fore goes on musing for any length of time without weari- ness. His motor quiescence ends in a dim, dreamy, hazy consciousness which is next door to unconsciousness, and easily passes into it. The reading of an uninteresting book occasions drowsiness, and the reading of any book soon sends to sleep one who is unused to reading or who is exhausted by great muscular exertion. His attention fails, we say ; in other words, he cannot keep up the nice motor adjustments so as to apprehend or grasp definitely the words and realise their meanings. The various means of trying to go to sleep have the same aim and exemplify the same principle : their aim is, first, to limit the area of cerebral activity so that most of it may cease ; second, to make the still continuing activity as monotonous as possible, until motor apprehensions of the recurring images fail. So also is it with fatigue and exposure to extreme cold : the be-