The question of color is an important factor in clothing. This is especially true in summer when exposure to the sun makes it especially necessary to consider our comfort. All dark-colored clothing absorbs the heat and the sun becomes very oppressive to the wearer. Then, too, black and dark-colored coverings shut out the light, another objectionable feature. In my reference to sun baths in the preceding chapter on Blood Purification I placed special emphasis upon the value of light as a vitalizing and stimulating factor in life and health. Ordinarily we not only smother our skins so far as the air is concerned, but we also shut out the light, hiding our bodies in a cellar, so to speak. Our bodies need light as well as air and for this reason dark colored clothing cannot be recommended. For warmth when in the sunshine during the winter, black is very effective. When out of the sunshine black is cooler in winter than light-colored fabrics because it quickly radiates the body heat. It is well known that a black stove radiates the heat much faster than a nickel-plated or brightly polished stove. White or light-colored garments are advised in summer, both because they are cooler and because they permit the light to reach the skin. The Arabs, Bedouins and others who live in unforested countries where they are much exposed to the tropical sun use turbans and flowing robes of white as a means of keeping cool. Pure white is often unserviceable, because it quickly becomes soiled, and therefore gray and tan- colored garments are recommended.