Suppose the old type of salesmanship, acting for a meat packer, was seeking to increase the sale of bacon. It would reiterate innumerable times in full-page advertisements: "Eat more bacon. Eat bacon because it is cheap, because it is good, because it gives you reserve energy." The newer salesmanship, understanding the group structure of society and the principles of mass psychology, would first ask: "Who is it that influences the eating habits of the public?" The answer, obviously is: "The physicians." The new salesman will then suggest to physicians to say publicly that it is wholesome to eat bacon. He knows as a mathematical certainty, that large numbers of persons will follow the advice of their doctors, because he understands the psychological relation of dependence of men upon their physicians.