Mason suggests 

> … a different origin for the divide.  Step One, leading
> economists in the 1930's were embarrassed and discredited by their serious
> failures to anticipate the crash, and to suggest remedies. Step Two, along
> came Keynes, resurrecting the ancient public works solutions, and attracting
> a huge following. The old timers were trained to preach free markets and
> austerity for labor, and had tenure and seniority, so to compromise they let
> young Turks teach fiscal policy, and old fossils teach free markets: macro
> and micro, two half-separate disciplines. 

Although the timing is correct, an important figure is left out of the picture: Ragnar Frisch. In his 1933 essay on the propagation and impulse problems in economics he wrote:

"When we approach the study of business cycle with the intention of carrying through an analysis that is truly dynamic and determinate in the above sense, we are naturally led to distinguish between two types of analyses: the micro-dynamic and the macro-dynamic types. The micro-dynamic analysis is an analysis by which we try to explain in some detail the behaviour of a certain section of the huge economic mechanism, taking for granted that certain general parameters are given. Obviously it may well be that we obtain more or less cyclical fluctuations in such sub-systems, even though the general parameters are given. The essence of this type of analysis is to show the details of the evolution of a given specific market, the behaviour of a given type of consumers, and so on.
	The macro-dynamic analysis, on the other hand, tries to give an account of the fluctuations of the whole economic system taken in its entirety. Obviously in this case it is impossible to carry through the analysis in great detail. Of course, it is always possible to give even a macro-dynamic analysis in detail if we confine ourselves to a purely formal theory. Indeed, it is always possible by a suitable system of subscripts and superscripts, etc., to introduce practically all factors which we may imagine: all individual commodities, all individual entrepreneurs, all individual consumers, etc., and to write out various kinds of relationships between these magnitudes, taking care that the number of equations is equal to the number of variables. Such a theory, however, would only have a rather limited interest. In such a theory it would hardly be possible to study such fundamental problems as the exact time shape of the solutions, the question of whether one group of phenomena is lagging behind or leading before another group, the question of whether one part of the system will oscillate with higher
amplitudes than another part, and so on. But these latter problems are just the essential problems in business cycle analysis. In order to attack these problems on a macro-dynamic basis so as to explain the movement of the system taken in its entirety, we must deliberately disregard a considerable amount of the details of the picture. We may perhaps start by throwing all kinds of production into one variable, all consumption into another, and so on, imagining that the notions "production," "consumption," and so on,' can be measured by some sort of total indices.".

This was soon taken up by Kalecki in Econometrica 1935, but with a twist on his own. He defined his first model as “A Macrodynamic Theory of Business Cycles”, explaining that “The term ‘macrodynamic’ was first applied by Professor Frisch in his work ‘Propagation problems and impulse problems in dynamics’ […] to determine processes connected with the functioning of the economic system as a whole, disregarding the details of disproportionate development of special parts of that system” (p. 327). Note that Kalecki’s interpretation of macrodynamics as disregarding disproportions does not have a counterpart in Frisch’s article, but probably aims instead at better defining Kalecki’s view of the cycle, not as a phenomenon arising from disturbances in the proportionate growth generalizing to the whole system (such as in Tugan-Baranovsky’s approach or in Bernstein’s view) but as the result of a more fundamental antinomy.

Another ingredient entering (implicitly only, but unavoidably so) in the micro-macro distinction is again due to Kalecki and, independently (if I remember correctly) to Keynes: the fallacy of composition with all its implications, which have so far been left out from this discussion.

When all this entered into textbooks and formed the basis for the distinction in teaching, I do not know.

Daniele Besomi