The Theory of the Leisure Class - An Economic Study of Institutions (1899), by Thorstein Veblen, is a treatise of economics and sociology, and a critique of conspicuous consumption as a function of social class and of consumerism, which are social activities derived from the social stratification of people and the division of labor; the social institutions of the feudal period (9th–15th c.) that have continued to the modern era.
Thorstein Bunde Veblen (July 30, 1857 – August 3, 1929) was an American economist and sociologist who, during his lifetime, emerged as a well-known critic of capitalism.
In his best-known book, The Theory of the Leisure Class (1899), Veblen coined the concepts of conspicuous consumption and conspicuous leisure. Historians of economics regard Veblen as the founding father of the institutional economics school. Contemporary economists still theorize Veblen's distinction between "institutions" and "technology", known as the Veblenian dichotomy.