f the system are then concentrated upon
the brain.[6]

[6] It appears to be a fact, that no two important organs can be
called into intense action at the same time, without injury to
both, as well as to the general system. This arises from the
circumstance that an organ, when in functional action, attracts
fluids (sanguineous and nervous) from other organs of the
system. Except in a few instances of high health in youth, the
power of the system is not adequate to supply more than one
organ in action with the appropriate fluids at the same time.

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What kinds of exercise are best? 190. What rule is given respecting
the time for exercise? 191. Why do the muscles require sleep? What is
the effect of an inversion of the law of rest?

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191. _The muscles require sleep to restore their expended energies._
Among the arrangements of creative wisdom, no one harmonizes with the
wants of the system more than the alternation of day and night. The
natural inclination of man to sleep, is in the stilly hour of night,
when all nature reposes, and to be in action during the light of day.
An inversion of this law of rest causes greater exhaustion of the
system than the same amount of exertion during daylight. This is
illustrated by the wearied and exhausted condition of watchers,
night-police, and other individuals who spend a part of the night in
some active business of life.

192. _The muscles should not be compressed._ Compression prevents the
blood from passing to the muscles with freedom; consequently, they are
not supplied with material to renovate and promote their growth.
Again, pressure stimulates the lymphatics to action; and by the
increased activity of these vessels the muscles are attenuated. In the
case of a man with a fractured limb, the muscles are not only
enfeebled by inaction, but diminished in size by compression from the
dressing. Limbs enfeebled in this way will not recover their size,
tone, and strength, until the bandages are removed, and a proper
amount of exercise taken.

193. The pressure of tight dresses, under the name of a "snug fit,"
enfeebles the muscles of the back, and is a common cause of projecting
shoulders and curvature of the spinal column. Thus every appendage to
the dress of ladies which prevents free motion of the muscles of the
chest and spinal column, weakens the muscles thus restrai