It is probable that when future historians of economic thought look back over this century, the thirties will appear as an era of rapid development in economic theory. Not only has there been unusual activity in monetary theory, theory of value. but extensive transformations have also been made in the basic theory of value. The outstanding publications in this field are, of course, Joan Robinson's Theory of Imperfect Competition and Chamberlin's Theory of Monopolistic Competition, the first produced in Cambridge, England, and the second in Cambridge, Massachusetts. These volumes mark the explicit recognition of the theory of the firm as an integral division of economic analysis upon which rests the whole fabric of equilibrium theory. General equilibrium is nothing more than the problem of the interaction of individual economic organisms, under various conditions and assumptions; as a necessary preliminary to its solution, an adequate theory of the individual organism itself is necessary.