In striking contrast to the models developed by the modern neoclassical writers are two models of general equilibrium developed in the 1930s, one by von Neumann, the other by Sraffa.1 Both are distinctly in the classical vein, but neither model involves recourse to marginal products, abstinence, rewards of waiting or the perfect substitutability of production functions that were later to be added by the modem neoclassicists.