Chemically all dirt is clean. Just as the foods and drinks of a good dinner, if mixed up together on a dish, would produce a filthy mess, so conversely, if we could separate any form of dirt into the pure solid, liquid and volatile chemical compounds of which it is composed, into pretty crystals, liquids and gases, exhibited in the scientific manner on spotless watch-glasses and in thrice-washed test-tubes,--we might indeed say that some of these chemicals had an evil odour, but we could not pronounce them unclean. Prepared in a laboratory, the sulphuretted hydrogen gas which makes the addled egg our national political weapon, is a quite cleanly preparation. Dirt is merely an unhappy mixture of clean substances. The housewife is nearest a scientific view of the matter when she distinguishes between 'clean dirt' and 'dirty dirt,' and does not mind handling coal, for instance, because, being clean dirt, it will not harm her. Cleanliness is a process by which we keep noxious microbes and certain poisons outside our systems or in their proper places within. (It has been shown that we cannot live without microbes, and that there exist normally in some parts of the body substances which are powerfully poisonous to other parts.) Rational cleanliness makes for health, for survival. It is, ultimately, an expression of the Will to Live. [Sidenote: _DIRT_] Far, however, from being rational, our notions on cleanliness are in the highest degree superficial. We make a great fuss over a flea; hardly mention it in polite company; but we tolerate the dirty housefly on all our food. We eat high game which our cook's more natural taste calls muck. We are only just beginning to realise the indescribable filthiness of carious teeth, than which anything more unclean, a few diseases excepted, can scarcely be found in slums. Even in this great age of pseudo-scientific enlightenment, we do not have a carious tooth extracted until it aches, though we have a front tooth cleaned and stopped on the first appearance of decay. What the eye doth not see.... Yet we presume to judge men by their deviation from our conventional standards of cleanliness.