Ricardian economics are the economic theories of David Ricardo, an English political economist born in 1772 who made a fortune as a stockbroker and loan broker. At the age of 27, he read An Inquiry into the Nature and Causes of Wealth of Nations by Adam Smith and was energised by the theories of economics.
His main economic ideas are contained in On the Principles of Political Economy and Taxation (1817). This set out a series of theories which would later become theoretical underpinnings of both Marx's Das Kapital and Marshallian economics, including the theory of economic rent, the labour theory of value and above all the theory of comparative advantage.