“The growing incidence of the external diseconomies generated by certain sectors of the economy and suffered by the public at large, regarded as the most salient factor responsible for the misallocation of our national resources, is one of the chief themes of this essay and the motif of this second part of the volume. All professional economists are, of course, aware of the role played by external diseconomies in the system; though alas, all too many of them tend to look at such effects merely as one of the chief obstacles to facile theorizing -- as the sort of possibility that detracts from the optimal properties of the popular theoretical construct, a perfectly competitive economy -- rather than as an existing social menace. Familiarity with so simple a concept, and ritual footnote references to it, seem to have imparted a feeling that the matter is well under control. Too many economists have, therefore, continued to ignore the events taking shape around them and to immerse themselves instead in the intellectual fascination of quasi-mathematical models of growth, and the theoretical problems involved in general solutions of optimal systems.”