are alike again.

Sleep, whose inventor received the benediction of Sancho Panza, and
whose power Dryden apostrophized,--

"Of all the powers the best:
Oh! peace of mind, repairer of decay,
Whose balm renews the limbs to labor of the day,"--

is a most important physiological factor. Our schools are as apt in
frightening it away as our churches are in inviting it. Sleep is the
opportunity for repair. During its hours of quiet rest, when muscular
and nervous effort are stilled, millions of microscopic cells are busy
in the penetralia of the organism, like coral insects in the depths of
the sea, repairing the waste which the day's study and work have
caused. Dr. B.W. Richardson of London, one of the most ingenious and
accomplished physiologists of the present day, describes the labor of
sleep in the following language: "During this period of natural sleep,
the most important changes of nutrition are in progress: the body is
renovating, and, if young, is actually growing. If the body be
properly covered, the animal heat is being conserved, and laid up for
expenditure during the waking hours that are to follow; the
respiration is reduced, the inspirations being lessened in the
proportion of six to seven, as compared with the number made when the
body is awake; the action of the heart is reduced; the voluntary
muscles, relieved of all fatigue, and with the extensors more relaxed
than the flexors, are undergoing repair of structure, and recruiting
their excitability; and the voluntary nervous system, dead for the
time to the external vibration, or, as the older men called it,
'stimulus' from without, is also undergoing rest and repair, so that,
when it comes again into work, it may receive better the impressions
it may have to gather up, and influence more effectively the muscles
it may be called upon to animate, direct, control."[11] An American
observer and physiologist, Dr. William A. Hammond, confirms the views
of his English colleague. He tells us that "the state of general
repose which accompanies sleep is of especial value to the organism,
in allowing the nutrition of the nervous tissue to go on at a greater
rate than its destructive metamorphosis." In another place he adds,
"For the brain, there is no rest except during sleep." And, again, he
says, "The more active the mind, the greater the necessity for sleep;
just as with a steamer, the greater the number of revolutions its
engine makes,