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. Habitual worriers use up force and become thin more quickly than those whose work is muscular. Those who spend their lives fretting over existing conditions, or worrying over things which never happen, use up much brain force and create disagreeable conditions within, resulting in digestive ills. These again react on the body and continue the process of impoverishment of the tissues. Certain it is that improper foods affect the disposition, retard the spiritual growth, and change the current of one’s life and of the lives about one. Therefore the intelligent care of the body—the medium through which the soul communicates with material surroundings—is a Christian duty. “The priest with liver trouble and the parishioner with indigestion, do not evidence that skilled Christian living so essential to the higher life.” Man has become so engrossed and hedged about with the complex demands of social, civic, and, domestic life, all of which call for undue energy and annoyance and lead him into careless or extravagant habits of eating and living, that he forgets to apply the intelligence which he puts into his business to the care of the machine which does the work. Yet the simple laws of nature in the care of the body are plainer and easier to follow than the complex habits which he forms. The “simple life” embraces the habits of eating as well as the habits of doing and of thinking. _The whole problem of perfect health and efficient activity is in keeping the supply of assimilated food equal to the demand, in keeping a forceful circulation that the nourishment may freely reach all tissues and the waste be eliminated, and in full breathing habits that sufficient oxygen be supplied to put the waste in condition for elimination._ FOOTNOTES: [1] It is impossible in this book to go into the anatomy and physiology of digestion exhaustively. The reader is respectfully referred to Miss Cocroft’s book on _Let’s Be Healthy_. This traces the food through the digestive canal, indicating the juices which act on it, putting it into the state in which it can be absorbed by the body and appropriated to its various uses. CONTENTS CHAPTER I PURPOSES OF FOOD PAGE