when these
feelings are violent. And though there are many who have never suffered
that extreme emotional excitement which is followed by arrest of the
heart's action and fainting; yet every one knows these to be cause and
effect. It is a familiar fact, too, that disturbance of the stomach
results from mental excitement exceeding a certain intensity. Loss of
appetite is a common consequence alike of very pleasurable and very
painful states of mind. When the event producing a pleasurable or
painful state of mind occurs shortly after a meal, it not unfrequently
happens either that the stomach rejects what has been eaten, or digests
it with great difficulty and under protest. And as every one who taxes
his brain much can testify, even purely intellectual action will, when
excessive, produce analogous effects. Now the relation between brain and
body which is so manifest in these extreme cases, holds equally in
ordinary, less-marked cases. Just as these violent but temporary
cerebral excitements produce violent but temporary disturbances of the
viscera; so do the less violent but chronic cerebral excitements produce
less violent but chronic visceral disturbances. This is not simply an
inference:--it is a truth to which every medical man can bear witness;
and it is one to which a long and sad experience enables us to give
personal testimony. Various degrees and forms of bodily derangement,
often taking years of enforced idleness to set partially right, result
from this prolonged over-exertion of mind. Sometimes the heart is
chiefly affected: habitual palpitations; a pulse much enfeebled; and
very generally a diminution in the number of beats from seventy-two to
sixty, or even fewer. Sometimes the conspicuous disorder is of the
stomach: a dyspepsia which makes life a burden, and is amenable to no
remedy but time. In many cases both heart and stomach are implicated.
Mostly the sleep is short and broken. And very generally there is more
or less mental depression.

Consider, then, how great must be the damage inflicted by undue mental
excitement on children and youths. More or less of this constitutional
disturbance will inevitably follow an exertion of brain beyond the
normal amount; and when not so excessive as to produce absolute illness,
is sure to entail a slowly accumulating degeneracy of _physique_. With a
small and fastidious appetite, an imperfect digestion, and an enfeebled
circulation, how can the developing body flour