Self-preservation, I have said, is the prime condition of happiness. A long life, therefore, is the desire of all sane minds. Old age, that which all abhor, is the hope of all. It alone justifies a man to himself and before others. The sage is he whose life is a consistent whole, and who carries out in his age the plans which he laid in youth. They are not many; but even they deceive us by their number. On the ocean of existence, who counts the shipwrecked? We see the votive offerings of the saved displayed with ostentation, but who notes the number of the drowned? In the scenery of the drama of human life, the most conspicuous buildings are the hospitals and asylums, and into these sooner or later most of the actors disappear. A learned French physician has maintained that the normal duration of human life is one hundred years; only a fifth of those born reach one half that age. Longevity is partly a birthright; it runs in families; but it is still more a question of occupation, mode of life, and personal hygiene. The Jews of Frankfurt average ten years more of life than the non-Jewish citizens, because they avoid unsanitary avocations and observe wiser rules of diet. I know a skillful physician who claims that he can lengthen the life of an individual a decade beyond the average of his ancestors by a judicious system of safeguards. Such an adviser is acquainted with the special dangers to which age is exposed. He knows, for instance, that at seventy-five exposure to cold is thirty-two times more dangerous than it is at thirty years of age. The sorrows of age are usually the returns of the investments of youth, these proving of that sort which levy assessments instead of paying dividends. “A short life and a merry one,” is the maxim of many a youngster. The hidden falsehood at the core of his philosophy is the belief that happiness belongs to youth alone. I have already referred to this dangerous fallacy. The bliss of youth, as portrayed by poets and romancers, did not belong to the youth I had, nor does it to the youths I know. The admiration of the early periods of life is one of a common class of illusions. There is greater charm in beauty half-concealed than wholly shown, in the dawn rather than in the day, in the promise of youth rather than in the maturity of manhood. Potentialities please more than actualities, because they excite our imagination and release us from the fetters of facts. He who would work securely for his own welfare will not be led astray by the belief that any one period of life contains solely or in any large measure the enjoyments of life as a whole. He will, therefore, not eat to-day the bread of to-morrow. Rather he will consider the problem of life akin to a problem of Euclid, the _quod erat demonstrandum_ of which is reached only in the last line. He will guard the fires of youth, that he may not in age have to sit by the cold ashes of exhausted pleasures.