No engineer can obtain from the machine under his control the highest results, unless every part of the mechanism is in perfect working order. How much more important, then, that the human organism should be in perfect adjustment, since through it the mentality is to find its highest expression? Without a knowledge of its construction and its working principles, how is the individual to raise the human machine to the highest plane of excellence and maintain it there? No one is allowed to run an engine without first passing an examination, which necessitates a certain amount of study and knowledge of the laws of mechanics; yet men undertake to run that complex machine, the human body, in utter ignorance of physiological law! Is it any wonder that there are so many breakdowns? What I contend for is the study of the fundamental facts concerning the ordinary functions of the body: of diet, dress and exercise in their relation to health, and the relative effects of good and bad air upon the system. It is of infinitely more consequence to understand the basic principles of digestion and the proper combination of foods, or to understand thoroughly the baneful effects of sleeping in a badly ventilated room, than to be the greatest living expert in conic sections. Practical physiology is the crying need of the times, especially for our children, if we expect them to be well developed--mentally, morally and physically. With such an equipment of knowledge the individual is prepared to withstand the wear and tear of life, and I may remark here that it is the _tear_ more than the _wear_ that figures in physical breakdown. All human beings are not endowed alike with nervous force; it is largely a matter of heredity, but what we have may be cultivated and developed. Failure to do so renders the individual liable to nervous breakdown, or neurasthenia, as it is popularly termed, a widespread disease, especially in America, where the strain of life is greater than elsewhere. Competition, a desire to go beyond one’s fellows in achievement, working beyond the strength, together with lack of care of the physical system, all conspire to keep constant the undue excitement of the nerves that ends in exhaustion. Children born of nervous parents, with weak nervous systems, should be fortified against the risks of inheritance by hygienic measures, during their developmental period, strengthening in every way their physical and mental endowments. Even those well developed in this respect should husband his or her resources--always keeping a reserve fund by avoiding undue fatigue, spending plenty of time in sleep, taking care of the body, and arranging for intervals of rest that shall include change of scene and environment.