A red-letter day it will be for us when we realize that exuberance represents for every one the income from his fund of vitality; that when one's exuberance is all gone, his income is temporarily exhausted; and that he cannot go on living at the same rate without touching the principal. The hard-headed, harder-worked American business man is admittedly clever and prudent about money matters. But when he comes to deal with immensely more important matters such as life, health, and joy, he often needs a guardian. He has not yet grasped the obvious truth that a man's fund of vitality ought to be administered upon at least as sound a business basis as his fund of dollars. The principal should not be broken into for living expenses during a term of at least ninety-nine years. (Metchnikoff says that this term is one hundred and twenty or so if you drink enough of the Bulgarian bacillus.) And one should not be content with anything short of a substantial rate of interest. In one respect this life-business is a simpler thing to manage than the dollar-business. For, in the former, if the interest comes in regularly and unimpaired, you may know that the principal is safe, while in the dollar-business they may be paying your interest out of your principal, and you none the wiser until the crash. But here the difference ceases. For if little or no vital interest comes in, your generous scale of living is pinched. You may defer the catastrophe a little by borrowing short-time loans at a ruinous rate from usurious stimulants, giving many pounds of flesh as security. But soon Shylock forecloses and you are forced to move with your sufferings to the slums and ten-cent lodging-houses of Life. Moreover, you must face a brutal dispossession from even the poor flat or dormitory cot you there occupy--out amid the snows and blasts-- "Where he stands, the Arch Fear in a visible form" there to pay slack life's "arrears of pain, darkness, and cold."