working hours of the day we are
expending force. The brain is using it in thought, the muscles are
calling for force in various activities, the emotions are expending
energy, and each of these activities is creating changes in the cells
of the body. We know that life in the body is only possible through
constant death of the atoms of which it is composed. We can only live
because we are constantly dying. Huxley says, "For every vital act,
life is used up. All work implies waste, and the work of life results
directly or indirectly in the waste of protoplasm (which is the cell
substance). Every word uttered by a speaker costs him some physical
loss, and in the strictest sense he burns that others may have light."

Each word, thought, activity, emotion causes expenditure, and unless
expenditure is in some way made good, there will be bankruptcy. How
shall we get back the energy we have expended and so restore our vital
forces to their equilibrium? The protoplasm of which our cells are
made we can obtain from the protoplasm of animal and vegetable
substances which we eat, but we cannot use the material unless we are
sometimes at rest, and by quiescence of brain and muscle give a chance
for worn-out cells to be removed and new material put in their place.
It is when we lay our bodies down in the beautiful repose of slumber
that this process can go on with most perfect results. Then, when all
the forces can be concentrated on the process of nutrition, will
nutrition be most perfect. When we awake refreshed after a night of
sound sleep we are really fed. It is quite doubtful if, in a normal
condition, we would want food until we had been at work some time and
by destroying tissue have created a demand for more new material.

If we were only half as anxious that food should be assimilated--that
is, made over into ourselves--as we are that it should be put into the
stomach, we would be very careful to secure for ourselves a due amount
of good sleep. And what is a due amount? That depends. I once heard of
a servant girl whose mistress complained of her because she did not
get up early in the morning, and the girl's excuse was, "But, ma'am, I
can't get up early because I sleep so slow."

It seems a ridiculous statement, and yet there is a germ of truth in
it. In some people the vital processes go on with such rapidity that
the old, worn-out material will be eliminated and the new material
built into the body in a comparatively