I agree with what Anne Mayhew and Kevin Quin wrote about Warsh's book. Indeed the book is not logically tight, but my point is not that Warsh has it confused, but that the economists about whom he is writing had it confused. Perhaps it has been empirically established that there are constant returns to scale, but, if so, that is very significant with respect to market structure, as another respondent has pointed out. There is, however, much in another realm towards which Warsh's book points. It is a history of economic thought, and, for all its illogic, it contains a very interesting story -- as Anne Mayhew has pointed out. When it is put with Helpman's MYSTERY OF ECONOMIC GROWTH, it is an indication of the impossibility of pursuing theory apart from the history of theory. When it is put with Lipsey's ECONOMIC TRANSFORMATIONS, it becomes evident that economic history is closely tied to economic theory. Because Lipsey and company are using theory to constrain understanding of the past, and using the past to establish, if not verify, theory. Lipsey's account of 'All Purpose Inventions" entails Romer's "endogenous growth model", about which Warsh has written. (I hope I understand all of this correctly.) I conclude that neither Economic History nor the History or Economic Thought are about to pass away, though they may not be closely tied to their institutionalization in academia. But I have been too dogmatic in writing this, and I wonder what you all think with respect to these matters. Further, there is much more that could be said about "Romer and Warsh", For example, I have read Kurtz's (I hope that is the name) critique of Romer. It recently appeared on this server. Clearly the limitations of particular theories are of some concern. Indeed the limitations of all theories in Economics are of fundamental concern. Which is not to say that because limited theories are of no use whatsoever. And again further, non-rivalrous goods, primarily information, and technological advance, which are at the heart of Romer's theory have yet to be considered. Robin Neill