… is from page 207 of my late Nobel-laureate colleague James Buchanan ‘s 1979 collection, What Should Economists Do?  (H. Geoffrey Brennan & Robert D. Tollison, eds); specifically, it’s from Jim’s 1976 paper “Methods and Morals in Economics ”:
The elementary fact is, of course, that homo economicus does exist in the human psyche, along with many other men, and that behavior is a product of the continuing internal struggle among these. The task of economic theory is not that of predicting specific patterns of behavior; it is that of providing an understanding of the processes within which the divergent behavioral plans of persons are integrated and reconciled.
DBx: Those of us who early on were exposed to the Austrian and Virginia Political Economy traditions of economics have never quite reacted as other economists have reacted to the findings of behavioral economists. These findings are not as surprising to us as they are to more-conventional economists. Nor do these findings do much, if anything, to undermine or ‘threaten’ our methods of analyses or the conclusions that we draw from our analyses.