Instinct strengthens the display motive. As every one can be interested in instinct hygiene, so every one is capable of this display motive to the extent that his position is affected by other people's opinion. It was love of display quite as much as love of beauty that gave Greece the goddess Hygeia, the worship of whom expressed secondarily a desire for universal health, and primarily a love of the beautiful among those who had leisure to enjoy it. _Commerce_ brooks no preventable interference with profits, whether by disease, death, impassable streets, or disabled men. The age of chivalry was also the age of indescribable filth, plague, Black Death, and spotted fever that cost the lives of millions. It would be impossible in the civilized world to duplicate the combination of luxury and filthy, disease-breeding conditions in the midst of which Queen Bess and her courtiers held their revels. The first protest was made, not by the church, not by sanitarians, but by the great merchants who were unable to insure against loss and ruin from the plagues that thrived on filth and overcrowding. By an interesting coincidence the first systematic street cleaning and the first systematic ship cleaning--maritime quarantine--date from the same year, 1348 A.D.; the former in the foremost German trading town, Cologne, and the latter in Venice, the foremost trading town of Italy. The merchants of Philadelphia and New York started the first boards of health in the United States. For what purpose? To prevent business losses from yellow fever. Desire for passable streets, drains, waterworks, and strong boards of health has generally started with merchants. For commercial reasons many of our states vote more money for the protection of cattle than for the protection of human life, and the United States votes millions for the study of hog cholera, chicken pip, and animal tuberculosis, while neglecting communicable diseases of men. No class in a community will respond more quickly to an appeal for the rigid enforcement of health laws than the merchant class; none will oppose so bitterly as that which makes profits out of the violation of health laws. TABLE II COST IN LIFE CAPITAL OF PREVENTABLE DISEASES[2]