1 92 THE POPULAR SCIENCE MONTHLY
get our second wind, or, having gotten it, whether we shall utilize to the full our powers of work, is a matter of our own will. I believe that few of us live up to our opportunities for accomplishing things. We are too inclined to yield to the early demands of fatigue. Even with- out exceptional hereditary endowment more of us might have, if we would, the endurance of a Weston, the discernment of a Darwin, the shrewdness of a Harriman, the determination of a Peary, or the insa- tiate desire to be on top which distinguished our late president. In his very sensible and characteristically delightful essay on " The Energies of Men," William James says:
The human individual lives usually far within his limits; he possesses powers of various sorts which he habitually fails to use. He energizes below his maximum, and he behaves below his optimum. In elementary faculty, in coordination, in power of inhibition and control, in every conceivable way, his life is contracted like the field of vision of an hysteric subject — but with less excuse, for the poor hysteric is diseased, while in the rest of us it is only an inveterate habit — the habit of inferiority to our full self — that is bad. . . . We live subject to arrest by degrees of fatigue which we have come only from habit to obey. Most of us may learn to push the barriers farther off, and to live in perfect comfort en much higher levels of power.
Herein lies the value of training. Training, whether of the child or the adult, the athlete or the thinker, consists largely in the develop- ment of a power of resistance to the toxic fatigue substances, and is not unlike the production of a condition of tolerance to a poisonous drug by the administration of successively increasing doses of it. Physical train- ing is not fundamentally different from general educational training. Habits of industry, which every educational system strives to develop in the child, are the converse of habits of fatigue, and in the last analysis habits of industry mean, in very large part, an acquired power of resistance to fatigue substances.
One difficulty which we all recognize is that of distinguishing be- tween real and pseudo-fatigue in ourselves or others, and knowing when a rational degree of real fatigue has been reached. The matter is a vital one to teachers, for a knowledge of the rate at which working power diminishes, of the presence or absence of a fatigue state at a given moment, might be of material help in directing the pupil's work. Various studies have been made of the fatigue of school children, but the results of all of them are unsatisfactory because of the lack of a satisfactory method of investigation. Even the physiologist in his laboratory, however exact he may be with the muscles of animals, has no method of measuring accurately the degree of fatigue in the intact body of a human being. Our sensations are not altogether a safe guide. We often interpret a temporary sleepiness, a temporary lack of power of attention, and uneasiness to be free from our task, as signs of real weariness and evidence that we should stop our labors. Yet we know that often a slight change of conditions will seem to give us renewed