Most of the rules of hygiene cost nothing to observe. But even when hygiene is costly at first, the cost is usually repaid in the end many times over. To ventilate a house in winter always costs a certain additional expenditure for coal, but it is better to pay the coal bill than the doctor's bills. To sleep out-of-doors costs some extra blankets, bedding, clothing, and roll curtains, but these not only save the cost of heating an indoor sleeping-room, but save also the cost of ill-health. There is no better economy than to keep one's working-power. To lose it means to lose its earnings and to have, in addition, the heavy expenses of medical attendance, medicines, and nursing, and often to lose life itself with its potential earnings of every sort. In short, an unhygienic life, for the sake of economy, is "penny-wise and pound-foolish." [Sidenote: "I Have No Time"] Many busy men object to hygiene because, they say, they have no time for it. They imagine that to devote an hour each day to exercise or relaxation is a waste of time and that they are really economizing their time by working that hour instead. We are here referring, not to those who can not control their working-time, but to those who deliberately choose to work when hygiene would require them to play. It is often those who fix their own working-hours, rather than those whose working-hours are fixed for them, who overwork the most. If these could know the suffering which sooner or later follows inevitably as the consequence of this mistaken policy, they would not pursue it for a single day. A slight loss of working-power comes immediately. A careful observer of mental workers found that an hour invested in exercise in the afternoon often pays for itself within a day, by rendering possible more rapid work. He also found an improvement in the quality of his work. The razor-edge of the mind needs daily honing through physical exercise. The same principle applies to all work. It is just as necessary to stop, at intervals, our physical and mental machinery for oiling and repairs, as to stop the machinery of a factory. [Sidenote: "Too Much Trouble"]