Let me add my voice to those already on record.  My book The Money Interest and the Public Interest:  American Monetary Thought 1920-1970 adds to the historical record the case of money.  My little article "Economists and Fed" in Journal of Economic Perspectives pushes the date back to pre-Fed origins.  I should have thought it was common knowledge that Ely and other founders of the American Economic Association were anything but laissez faire proponents.  

So I ask a question--what is the origin of the rhetorical trope used by Krugman, and in fact by many others.  Who first thought it was a good idea to pretend that all was darkness before Keynes brought light?

Perry Mehrling