The term ‘physical culture,’ as usually applied, is supposed only to mean the development of the muscles and viscera; really it only begins there. After the organs of nutrition have been got into a healthy state the motor organs are developed. Finally the nervous system should be trained. Mere muscle will not make even a good runner. He must practise carefully till he can take his full stride, and do so without wasting energy by any needless movements. Then he must make the action which his brain has decided is the most effective for his build the property of his spinal cord, that in a race he may use his strength economically, with his thoughts free to deal with the tactics of his opponents and the peculiarities of the course, or he will not make his supreme effort at the most advantageous moment. This is only one instance. Many men having a normal body develop organs of perception, not motion: the musician and the wine-taster, as well as the juggler and the athlete, are products of physical culture. Even the philosopher must foster the physical basis of intellect. The education of the nervous system goes on all through life; and just as oft-repeated actions become automatic, so are habits of thought formed which are almost as regular; in fact, we might almost call them cerebral reflexes. Without constant exercise, men lose their flexibility of mind as well as of body. But we have already passed the boundaries of our subject, and it is time for us to pull up, lest we trench further upon another science; for the study of the mind is the province, not of the physiologist, but of the psychologist. II. Notwithstanding the strange powers of protoplasm, and notwithstanding that these are accumulated and intensified in the body, as we saw in the last chapter, there are immovable limitations to vital activity. This is a fact familiar to all. We can trace diminishing vitality through a series of stages, from slight fatigue right up to death itself. Sleep is perhaps one of the most interesting, though it is little understood. During sleep and the hypnotic trance, we know that the cells of the hemispheres pause in their work and chemically recruit themselves; that there is an interruption of consciousness; and that changes occur in the respiratory and circulatory, and, in fact, in most of the functions. But exactly how these states are induced we do not know. It has been suggested that during sleep less blood passes through the brain; but this is unlikely, and still less probable is it that the nerve cells draw in their processes and shut up like sea-anemones, as another daring theorist supposed. We can only draw parallels between the cells of the central nervous system and any others; all need rest.