Normal exercise often stimulates the brain, and by promoting more vigorous circulation, and so greater physical activity all over the body, helps the brain to work more easily.  Therefore some men can think better while walking.

This is quite unlike the superfluous strain of nervous motion, which, however it may seem to help at the time, eventually and steadily lessens mental power instead of increasing it.  The distinction between motion which wholesomely increases the brain activity and that which is simply unnecessary tension, is not difficult to discern when our eyes are well opened to superfluous effort.  This misdirected force seems to be the secret of much of the overwork in schools, and the consequent physical break-down of school children, especially girls.  It is not that they have too much to do, it is that they do not know how to study naturally, and with the real concentration which learns the lesson most quickly, most surely, and with the least amount of effort.  They study a lesson with all the muscles of the body when only the brain is needed, with a running accompaniment of worry for fear it will not be learned.

Girls can be, have been, trained out of worrying about their lessons.  Nervous strain is often extreme in students, from lesson-worry alone; and indeed in many cases it is the worry that tires and brings illness, and not the study.  Worry is brain tension.  It is partly a vague, unformed sense that work is not being done in the best way which makes the pressure more than it need be; and instead of quietly studying to work to better advantage, the worrier allows herself to get more and more oppressed by her anxieties,—­as we have seen a child grow cross over a snarl of twine which, with very little patience, might be easily unravelled, but in which, in the child’s nervous annoyance, every knot is pulled tighter.  Perhaps we ought hardly to expect as much from the worried student as from the child, because the ideas of how to study arc so vague that they seldom bring a realization of the fact that there might be an improvement in the way of studying.

This possible improvement may be easily shown.  I have taken a girl inclined to the mistaken way of working, asked her to lie on the floor where she could give up entirely to the force of gravity,—­then after helping her to a certain amount of passivity, so that at least she looked quiet, have asked her to give me a list of her lessons.  Before opening her mouth to answer, she moved in little nervous twitches, apparently every muscle in her body, from head to foot.  I stopped her, took time to bring her again to a quiet state, and then repeated the question.  Again the nervous movement began, but this time the child exclaimed, “Why, isn’t it funny?  I cannot think without moving all over!” Here was the Rubicon crossed.  She had become alive to her own superfluous tension; and after that to train her not only to think without moving all over, but to answer questions easily and quietly and so with more expression, and then to study with greatly decreased effort, was a very pleasant process.