… is from pages 218-219 of Hayek’s 1978 collection, New Studies in Philosophy, Politics, Economics and the History of Ideas; in particular, it is from Part 4, Section I of his essay “The Campaign Against Keynesian Inflation”; original emphasis:
It was John Maynard Keynes, a man of great intellect but limited knowledge of economic theory, who ultimately succeeded in rehabilitating a view long the preserve of cranks with whom he openly sympathised. He had attempted by a succession of new theories to justify the same, superficially persuasive, intuitive belief that had been held by many practical men before, but that will not withstand rigorous analysis of the price mechanism: just as there cannot be a uniform price for all kinds of labour, an equality of demand and supply of labour in general cannot be secured by managing aggregate demand.
