And as the shift to industrialization took place, so too was there a move toward a classical period of redefinement of economic theory. The leading proponents of classical theory were Adam Smith, whose writings in The Wealth of Nations has become the definitive anthology of free enterprise, and David Ricardo. Ricardo, a successful stock broker, published in 1817 Principles of political Economy and Taxation, in which he agreed with Smith on the right to pursue one’s own economic happiness. Others of the time of almost equal light were Nassau Senior (1790-1864) and John Stuart Mill, who is considered to be the last great economist of the genre. Jean-Baptiste Say was influenced by Smith, who promoted the classical school of thought in Europe.