 Despite the early start of the qualitative theory of probability, the quantitative theory did not develop until Blaise Pascal’s study of gambling in the seventeenth century (Hacking 1975). Only in the eighteenth century did it penetrate the insurance industry (even though insurers realized that a fortune could be made by accurately calculating risk). Only in the nineteenth century did probability make a mark in physics. And only in the twentieth century do probabilists make important advances over Arcesilaus.