There has been such a tremendous move in mechanical devices the last twenty years that this necessity of adapting our methods of living so as to safely accomplish the things our brains are called upon to do, has not been fully appreciated. Take the case of an engineer who has been on duty for twenty-four hours. The old idea was that he simply became tired, that if he could keep his eyes open, everything would go all right. Now I have told you that fatigue produces a poison in the body; so here we see that when an engineer meets with an accident it was not due to merely being tired, but because his brain was being saturated with poisons, and when the moment came to act there could not be the ready response of hands or arms to avoid the accident. But one class of men and women have known the absolute necessity of keeping the brain clear of poison. This class belongs to the professional circus people――trapeze performers, animal trainers, riders. These individuals live an ideally moral life. Not that they are any better than the rest of us, but because they know they have so to live in order to do their work. It is a very old profession, perhaps the oldest in the world, and experience, tradition, training and marrying into their own class――a very important factor――has brought about their unconscious acceptance of the physically pure life. Undoubtedly after a generation or two in the use of our wonderful mechanical and electrical aids for easier living, we shall all be brought to the same method of grading our habits. Those who have not the mental vision to see this necessity will cease to enjoy the world’s improvements. They will all become victims of their own stupidity or foolishness. Not only does all this danger in dulling our brain-tools apply to the engineer, electrician, airman, auto driver and the hundreds of other active callings, but it applies also to the writer, painter, musician. In these latter professions the danger is to the individual, but the result is the same――ruin in the end. The writer loses his force, his biting words; the painter shows a lack of his former color-tone, the musician finds that his latest work is severely criticised. All these conditions may occur and yet the creator of brain output still remain an average man, not noticeably dissipated. In fact, he may live a strictly moral life, yet show in his prime a deterioration which neither he nor his friends can explain. This fact brings us to the point of explaining the little and big factors which produce these causes of failure.