Capital (German: Das Kapital) is a set of books (the first of which was published in 1867) by Karl Marx as a critique of capitalism (critique of political economy). Many consider this work to be the landmark of Marxist socialist thought. In this work there are many complex economic concepts, such as surplus value, constant capital and variable capital, an analysis of wages, primitive accumulation, in short, all aspects of the capitalist mode of production, including a critique of Adam Smith's labor theory of value and other subjects from the classical economists.