Can we attain to greater health and efficiency? If health is, then, so important to the individual and society, its pursuit is not a selfish or a trivial matter; it is rather a serious and unavoidable duty. The gospel of health is sorely needed in our modern world. Young men and women use up their apparently limitless capital with heedless waste; those who start with a lesser inheritance neglect the means at their command for increasing their stock of strength and winning the power and exuberance of life that might be theirs. There are, of course, many cases of undeserved ill health; we ill understand as yet the causes and enemies of bodily vigor, and many a gallant fight for health has gone unrewarded. But in the great majority of cases a wise conduct of life would retain robust strength for the threescore or more years of our allotted course, increase it for those who start poorly equipped, and regain it for those who by mischance, blunder, or imprudence have lost their heritage. Yet half the world hardly knows what real health is. Our hospitals and sanitariums are crowded, our streets are full of half-sick people-hollow chests, sallow faces, dark-rimmed eyes, nervous, run-down, worn-out, brain-fagged, dragging on their existence, or dying before their time, robbed by stupidity and ignorance of their birthright of full-breathed rosy-cheeked health, and robbing the society that has reared them of the full quota of their service. Health is not merely freedom from disease; we have a right to what Emerson called "plus health." And among the men who rightly awaken our enthusiasm are those who out of a frail childhood have built up for themselves by perseverance and will a manhood of physical power, endurance, and efficiency. The principles of health for the normal man are few and simple, the reward great; what stands in the way is partly our apathy and indifference, partly our incontinent appetites, partly the unwholesome and deadening social influences in which we find ourselves enmeshed. For those who care enough, almost unlimited vistas open up; as Spinoza has it, "No one has yet found the limits of what the body can do." William James was convinced [Footnote: See his essay, "The Energies of Man," in Memories and Studies.] that the potentialities of human energy and efficiency are but half realized by the best of us. We must learn better to run the human machine. Our prevalent disregard of the conditions of bodily vigor, our persistent carelessness in the elementary matters of hygiene and health, is nothing short of criminal. "We would have health, and yet still use our bodies ill; Bafflers of our own prayers from youth to life's last scenes."