illustrations of all the varieties of disobedience to
Nature's laws in _activity_ would fill not one small book, but several
large ones; and then, unless we improve, a year-book of new examples of
nervous strain could be published. But fortunately, if we are nervous
and short-sighted, we have a good share of brain and commonsense when
it is once appealed to, and a few examples will open our eyes and set
us thinking, to real and practical results.

V.

THE USE OF THE BRAIN

LET us now consider instances where the brain alone is used, and the
other parts of the body have nothing to do but keep quiet and let the
brain do its work. Take thinking, for instance. Most of us think with
the throat so contracted that it is surprising there is room enough to
let the breath through, the tongue held firmly, and the jaw muscles set
as if suffering from an acute attack of lockjaw. Each has his own
favorite tension in the act of meditation, although we are most
generous in the force given to the jaw and throat. The same superfluous
tension may be observed in one engaged in silent reading; and the force
of the strain increases in proportion to the interest or profundity of
the matter read. It is certainly clear, without a knowledge of anatomy
or physiology, that for pure, unadulterated thinking, only the brain is
needed; and if vital force is given to other parts of the body to hold
them in unnatural contraction; we not only expend it extravagantly, but
we rob the brain of its own. When, for purely mental work, all the
activity is given to the brain, and the body left free and passive, the
concentration is better, conclusions are reached with more
satisfaction, and the reaction, after the work is over, is healthy and
refreshing.

This whole machine can be understood perhaps more clearly by comparing
it to a community of people. In any community,--Church, State,
institution, or household,--just so far as each member minds his own
business, does his own individual work for himself and for those about
him, and does not officiously interfere with the business of others,
the community is quiet, orderly, and successful. Imagine the state of a
deliberative assembly during the delivery of a speech, if half-a-dozen
of the listeners were to attempt to help the speaker by rising and
talking at the same time; and yet this is the absurd action of the
human body when a dozen or more parts, that are not needed, contract
"in sympathy" with