... writing in the General Theory after leaving his Wicksellian phase, Keynes said that “... I had not then understood that, in certain conditions, the system could be in equilibrium with less than full employment….I am now no longer of the opinion that the concept of a ‘natural’ rate of interest, which previously seemed to me a most promising idea, has anything very useful or significant to contribute to our analysis (pp. 242-43).” Today’s New “Keynesians” have tremendous intellectual firepower. The puzzle is why they revert to Wicksell on loanable funds and the natural rate while ignoring Keynes’s innovations. Maybe, as he said in the preface to the General Theory, “The difficulty lies, not in the new ideas, but in escaping from the old ones… (p. viii).”His point is that while there are good reasons to believe in the forces of stagnation, the reasons are not the Wicksellian ones given in New Keynesian models. Worth reading.