A buck-saw, a spade, or even a broom is better than a teacher of breathing and a better corrector of sleeplessness. CHAPTER XXIV. EATING AND SLEEPING For his sleep Was aery light, from pure digestion bred. MILTON. We do not have to depend upon mere irresponsible guesses for the new faith in the possibility of longer life for man. Scientists have been experimenting along this line for some years, and Metchnikoff assures us that the average human life should exceed “three-score years and ten” by four decades. He points out that the greatly increased number of persons who remain physically and mentally active past the age of seventy-five and eighty years is itself a proof that life may be prolonged. He recognizes that merely to extend existence is not a sufficient end to work for—it must be an active, worthwhile existence, and he has experimented toward this end. All of us can recall instances of “old people” who have preserved their physical and mental faculties until their last years. We have been in the habit of regarding these people as exceptions and have perhaps not noticed that these “exceptions” are already almost frequent enough to prove that there is no such rule for longevity. Whenever we investigate a new and wonderful thing, we find that its causes are simple and ordinary. So Metchnikoff and kindred experimenters are beginning to show us that prolonging life is a comparatively simple matter. It comes back again to diet and sleep on the physical side and to understanding of the universal laws on the mental and the emotional side of life. All scientific men agree that nearly all of us eat too much, or eat improper food. Most of them say that we sleep too much, or try to sleep too much. They advise simple diet, varied but not heavy. It is probable that the early human being ate as the wild animals do, to appease hunger, and had to eat whatever he could find without regard to taste. As civilization advanced and he learned ways of getting increased returns from Nature, he began to select and choose what he should eat. In this way he developed “appetite” as apart from natural hunger, and as his knowledge increased, and his taste became more and more refined, appetite gradually took the place of hunger.