Property and Prices shows arbitrage and speculation in the stockmarket to be a capitalist economy's most fundamental mechanism of price determination and resource allocation. Once a stockmarket is incorporated into general-equilibrium theory, the classical analysis of value (a la Ricardo, Marx and Sraffa) and the neoclassical theory of price (descending from Walras, Hicks and Arrow-Debreu) can be seen to possess the same mathematical structure. The modern theory of arbitrage pricing in financial markets thus is capable of bringing together the two great rival schools of economic thought.