I look upon the Keynesian theory as essentially a system of equations. While I may have once been satisfied with the explanatory value of a small version of that system expressed in just 2 or 3 equations, I now feel that intelligent discussion cannot be carried on, unless this system is expanded to include 20 or more equations. In current econometric model construction, I am working with some macro system that have more than 100 equations.
These larger systems, extended along the lines indicated in this essay, may not be easily recognized as the Keynesian theory, yet I feel that they surely are. They are manifestations of points I have reached, in collaboration with many colleagues, after starting out from the simplest forms of the Keynesian Revolution and working systematically through econometric studies of available data. They are, in a real sense just extensions of the Keynesian theory in a natural way.
The new versions must have some relative prices, a good theory of price level determination, dynamic features, a government sector, a trading sector, an effective link to the monetary sector, and a more detailed money market. I think that new advances will be made in these directions and that they will be econometrically based.
A postscript on the role of Keynes in the Keynesian Revolution may be in order. Would the Revolution have taken place without Keynes? In the same way that I feel we are now evolving a system, from Keynes' original model follows a natural course of intellectual development, I think that the Keynesian system as a mathematical model would have come into being without Keynes, as a natural outgrowth of the economic discussions of the 1930's.
The dramatic weight of Keynes' personality undoubtedly added much to the speedy acceptance of the theory and was responsible for the philosophical and policy aspects of the Keynesian Revolution, but the cold analytical theory would probably have come in any case. The Kalecki model of the business cycle really sets down all the essential ingredients of the simple model, and makes it dynamic in the bargain.20) Kalecki's mathematical paper in Econometrica attracted little attention compared with Keynes' splash, but eventually the theorists would have seen through the matter and given Kalecki's pre-General Theory model its full due.
Pronouncements by Frisch and Ohlin on policies for meeting the economic collapse of the early 1930's show clearly that analysis of the situation was congealing along lines that would have led to the same kinds of theoretical models. It was as though these two scholars were interpreting the periods events in terms of the saving-investment theory of income determination. By a slower, more gradual process their ideas would have merged with Kalecki's formal model into something that is not fundamentally different from the Keynesian system.
These remarks are not intended to detract from the remarkable Keynesian contribution, but they are primarily meant to give proper credit to the other scholars and attempt to take some comfort in the feeling that good ideas will eventually predominate regardless of any single personality.

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