The brain, like all other organs of the body, requires alternate
exercise and repose; and, in physical endurance, it is subject to
general physiological laws. When exercised with moderation it acquires
strength, vigor, and an accelerated activity. Excessive mental exertion
is liable to result in softening of the brain, and various nervous
diseases, sometimes culminating in insanity, and in many instances
proving fatal to life. The mere votaries of pleasure who avoid all
effort of the mind, fall into the opposite error. In all cases of
intellectual activity, the exertions should be directed to some subject
interesting to the student. In this manner duty will become a pleasure,
which in turn will re-invigorate the mental functions.

When the mind in confined to one subject for any considerable length of
time together, it becomes fatigued, and requires relaxation, recreation,
rest. This may be obtained by directing the attention to some other
subject, either study or amusement, the latter of which is preferable.
The amusement, however, may be of an intellectual or physical character
or both combined, and will, if properly conducted, restore vigor to both
mind and body.

Prominent among physical phenomena is the mutual relation between the
brain and the organs of nutrition. Mental exertion should be avoided for
at least one hour after a hearty meal, and all mental labor which
requires concentration of thought ought to be accomplished in the
earlier portion of the day, when the brain is refreshed and repaired by
the night's repose. Mental, like physical endurance, is modified by age,
health and development. A person accustomed to concentration of thought,
can endure a longer mental strain than one inured to manual labor only.
One of the most injurious customs, is the cultivation of the intellect