The former custom of employing a physician as a retainer had its distinct advantage, his duty being to instruct in right living so as to _avoid_ disease rather than to _cure_ it. To-day scientific instruction in food and hygiene is within the reach of all, and every mother and teacher is a retainer, or guard of the health of those in her charge. Happily, the United States Government, realizing that its power as a nation depends upon the strength and health of its citizens, has established experimental and analytical food departments. As a result of the findings of the governmental chemists, there was enacted in 1906, the Food and Drug Act, which aims to raise the standard of food purity, by prescribing the conditions under which foods may be manufactured and sold. The law compels the maker of artificially colored or preserved food products to correctly label his goods. The national law was the instigation of state laws, which have further helped to insure a supply of pure food products. Every particle of body substance is constantly changing. The new material for cells and tissues, the substance to supply the energy needed in the metabolic work of tearing down and rebuilding, the energy used in the digestive process of converting the food into condition to be assimilated, and the energy used in muscular, brain, and nerve movement, must all be supplied by food. Every brain effort in the process of thinking, every motion, and every muscular movement requires energy which the food must supply. Brain workers, or habitual worriers, use up force and become thin quite as quickly as those whose work is muscular. The term “brain workers” is commonly applied to professional men or women,—to authors, editors, teachers, or to those engaged in business, but the woman who manages her household judiciously, or the woman who spends her life fretting over existing conditions, or worrying over things which never happen, uses quite as much brain force. The difference is that the former accomplish results outside of themselves, while the latter simply stirs up disagreeable conditions within, resulting in physical ills. _The whole problem of perfect health and efficient activity is in keeping the supply 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._ The body is certainly a marvelous machine! It is self-building, self-repairing, and, to a degree, self-regulating. It appropriates to its use foodstuffs for growth and for repair. It eliminates its waste. It supplies the energy for rebuilding, and eliminating this waste. It directs its own emotions. It supplies the energy for these emotions. It discriminates in the selection of food and casts out refuse and food not needed.