f the brain alone should be at work, the force is not focussed
if it is at the same time flying over all other parts of the body in
useless strain of innumerable muscles. Tell another man, one who works
naturally, to solve the same problem,--he will instinctively and at
once "erase all previous impressions" in muscle and nerve, and with a
quiet, earnest expression, not a face knotted with useless strain, will
concentrate upon his work. The result, so far as the problem itself is
concerned, may be the same in both cases; but the result upon the
physique of the men who have undertaken the work will be vastly
different.

It will be insisted upon by many, and, strange as it may seem, by many
who have a large share of good sense, that they can work better with
this extra tension. "For," the explanation is, "it is natural to me."
That may be, but it is not natural to Nature; and however difficult it
may be at first to drop our own way and adopt Nature's, the
proportionate gain is very great in the end.

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