David Ricardo (1772-1823), English economist. Ricardo was one of the most influential classical economists as well as a successful businessman. He is known for introducing mathematical modeling to economics and publishing On the Principles of Political Economy and Taxation in 1817, which went through three revisions. He proposed the concept of Ricardian equivalence, suggesting that how a government pays for its spending might not affect the economy. Additionally, Ricardos theory of comparative advantage argued that nations could gain from free trade.