It directs its own emotions.
It supplies the energy for these emotions.
It discriminates in the selection of food and casts out refuse and foodstuffs not needed.
It forms brain cells and creates mental force with which to control the organism.
It keeps in repair the nerves, which are the telegraph wires connecting the brain with all parts of the body.
It converts the potential energy in the food into heat with which to keep itself warm.
Withal it is not left entirely free to do its work automatically. It has within it a higher intelligence, a spiritual force, which may definitely hamper its workings by getting a wrong control of the telegraph wires, thus interfering with the digestion, the heart action, the lungs, and all metabolic changes. The right exercise of this higher intelligence, in turn, depends on the condition of the body, because when the mechanism of the body is out of repair it hampers mental and spiritual control.
About one-third of the food eaten goes to maintain the life of the body in its incessant work of repairing and rebuilding, the remaining two-thirds being held in reserve for other activities.
One of the most remarkable and the least understood of any of the assimilative and absorptive functions, is the ability shown by one part of the body to appropriate from the foods the elements necessary for its own rebuilding, while the same elements pass through other organs untouched. The body has the power, also, not only to make use of the foods, but to use up the blood tissue itself. Just how this is done is also a mystery.
There is surely a great lesson in industry here, and one of the most profound studies in economics, physics, and chemistry.