[Sidenote: Cleanliness in the house.] Yet even if windows and doors are kept open, something more is requisite. For unless a house is scrupulously clean and the rooms regularly turned out, it cannot be healthy. If a piece of machinery is left untouched for some months it will never be as good as it was before. The grease has become foul, whilst dust and dirt have accumulated, and these insidious elements have combined to destroy the quality of the metal. That means that some time or other some bar or joint or nut will crack, and once that has happened the mischief rarely stops there, but goes on to the weakening of other parts and the deterioration of the whole machine. And when human beings live in houses that are not fresh and wholesome they are constantly inhaling dust and fusty smells, which act as a slow, subtle poison and lower the vitality of the various tissues of the body. It is so gradual that they may not notice it, until at last something gives way, and after that the downward tendency becomes comparatively rapid. When the cataclysm occurs, they date it from the day when the first crack, if we may call it so, appeared. Rather should they look back to the long years spent in an unhealthy atmosphere within their own homes. [Sidenote: Hygiene in the home.] There is no fault, however apparently trivial it may seem, in matters of hygiene which does not add its quota towards the final breakdown of the human machinery. The faulty, leaking gaspipe which causes oft-repeated morning headaches; the choked-up scullery sink, with its abominable mixture of soap, grease and vegetable washings; the defective drain and pipes; each and all do their evil part in undermining the constitution and rendering it more prone to the onset of disease. There is another aspect of this question to which too little prominence has been given. It is that of tidiness, and its effect on the nervous system. We all know that a tidy desk indicates a methodical, well-regulated mind, and that one which is in a litter is usually the sign of a man whose ideas are confused and jumbled up. Everyone does not realise that the sight of a disorderly room, with waste paper lying on the floor and an unswept hearth, has an irritating effect on the nerves of a man or woman who comes home jaded and tired. We shall have occasion shortly to point out that it is this harassed state which is one of the most potent factors in causing nervous breakdowns. And it is just when the home-comer needs to have everything as smooth as possible to put him or her into a calm and equable frame of mind that their fretted nervous systems are still further irritated by signs of disorder in their homes. Tidiness is more than a mere virtue, it is an indispensable adjunct to health.