[21] You can easily test this by a very simple experiment. Take a pair of dividers; or, if you haven't these, a couple of long pins or needles will do. Set them with their points a quarter of an inch apart. Then touch these points, first closing your eyes, so that you will not be able to see them, to the tip of one of your fingers, and you will readily feel that _two_ points touch the skin. Turn your hand over and touch the back of it with the two points, and they will feel like one point. Carry the test further, over other parts of the body, and you will find that they are much less sensitive; thus you will find that at the back of the neck, or over the shoulder-blades, you will have to put the points nearly an inch apart before you can tell that there are two of them. This simply means that you have to touch two separate touch bulbs before you can get the idea of "two-ness." As these bulbs are an inch or more apart in the skin of the back, you have to spread the points of the dividers that distance. You can also prove that the touching of two nerve-buds gives the idea of "two-ness" by crossing two of your fingers and placing a pea, or small round piece of chalk, between their crossed tips. If you close your eyes and roll the pea on the table, or desk, you will think you have two peas between your fingers. CHAPTER XVI HOW TO KEEP THE SKIN HEALTHY CLOTHING Clothes should be Loose and Comfortable. Man is the only animal that has no natural suit of clothing. Birds have feathers, and animals have fur, or hair, which they shed in summer and thicken up in winter without even thinking about it, so that they do not have to bother with either overcoats or flannels. The wise men say that man originally had a full suit of hair like other animals, and that he gradually got rid of it, as he became human. Whether this be true or not, the fact remains that he has none now; and consequently he must invent and manufacture something to take its place. Originally, in the time of our savage ancestors, clothing was worn chiefly as protection from cold at night, so that all the earlier forms of clothing were of a more or less blanket-or cloak-like form, and wrapped, or swathed, the whole body without fitting closely to the limbs. It is interesting to remember this fact, because even our most highly civilized forms of clothing still show this same tendency. The skirt, for instance, is simply a survival of the lower end of the blanket, which has never been cut down to fit the limbs.