I am grateful for Daniele's corrections. I knew that the League of Nations had commissioned the study in 1930 but the actual chronology of Haberler's involvement in the writing of Prosperity and Depression was not known to me. I had, however, read somewhere that he had gone back over the manuscript after the publication of the General Theory so that confirmation or otherwise would be welcome. Whatever the case, it is clear that Keynes's imprint is found in many places, and not just where he is being explicitly discussed. That the General Theory permeates the manuscript means that it is not an unadulterated depiction of the pre-Keynesian classical theory of the cycle. Close, but not total, so in that sense it is unfortunate for later scholarly research. 

If I gave the impression that Haberler dealt with every theory of the cycle ever articulated, then I regret that impression. But it was a compendium of all of the theories of the cycle that were being discussed at the time and thus provides a very useful reference point helping to separate pre-Keynesian theory from what came later. The what-came-later may be seen in the later editions of the book in which Keynesian economic theory takes over the entire last section. 

But what I especially welcome in Daniele's post is that she has been able to add to the statement made by Haberler to the effect that "there is complete unanimity among economists? over the existence of a business cycle. The very fact that there was complete unanimity should have meant that others would have said the same or similar things so it is not surprising that they did. That Haberler could say it again as late as 1937 without fear of contradiction casts an interesting reflection on our own modern theories dealing with fluctuations in economic activity today. This was, of course, the core point I was trying to make. 

Steven Kates