Athletes competing on the running track are often seen to falter and fall back, apparently exhausted; after which, they suddenly seem to breathe more freely, they overcome their limpness and start out on a fresh spurt which may cause them to head off steadier runners. What happens in such a case is this: great physical exertion causes a form of asphyxiation. Asphyxiation and the concomitant fear, liberate adrenin which restores the tone of tired muscles and also glycogen (sugar) which supplies the body with new fuel. If the exertion continues long enough to use up all these emergency chemicals, the muscular relaxation necessary for sleep may be obtained. Otherwise, the organism prepared for a struggle with reality, will not lend itself to a flight from it. Although we are "worn out" we toss about in our bed, try all possible sleeping positions and only sleep when the energy which was supplied for a long struggle has been entirely burnt up. The majority of people, after all, busy themselves with tasks which do not really deplete their stores of energy, but which prove monotonous. That monotony is then interpreted as fatigue. In such cases, rest seems to be more easily attained through a change of activity than through mere cessation of activity. A business man has been closeted in his office attending to many tedious details, reading letters and answering them, etc., and by five o'clock he feels "tired." He will then go home, change his day suit for evening wear, attend a dinner at which he will do perhaps much talking, then watch actors for three hours and feel "rested." Or at the end of a "heavy" week, he will gather up his golf outfit and walk miles in the wake of a rubber ball. He returns to his work "rested," although he has only exchanged one form of activity for other forms of activity. Of actual "rest" he has had none. Children "tired" of sitting in a class room will romp wildly, shout at the tops of their lungs, jostle and fight one another and return to meet their teacher "rested." Undirected activity in the young, pleasurable activity in the adult do not seem to make rest necessary, and in fact are a form of "rest." Egotistical gratification easily takes the place of rest. Heads of large businesses have sometimes mentioned to me that they worked much harder than some of their employés. Some of them kept on revolving commercial schemes in their heads or attending business meetings long after their office workers had left. "And yet," they added, "we are not complaining about being tired." Nor were they as tired, after fifteen hours of "free labor" as their employés were after six or eight hours of routine work allowing them very little initiative and independence of action.