Marx's analysis of the commodity (in German: Kaufware, i.e. merchandise, ware for sale) is intended to help solve the problem of what establishes the economic value of goods, using the labor theory of value. This problem was extensively debated by Adam Smith, David Ricardo, and Karl Rodbertus-Jagetzow, among others. Value and price are not equivalent terms in economics, and theorising the specific relationship of value to market price has been a challenge for both liberal and Marxist economists.