… is from pages 214-215 of the original edition of Henry Hazlitt’s classic 1946 volume, Economics in One Lesson :
[W]hen we study the effects of various proposals, not merely on special groups in the short run, but on all groups in the long run, the conclusions we arrive at usually correspond with those of unsophisticated common sense. It would not occur to anyone unacquainted with the prevailing economic half-literacy that it is good to have windows broken and cities destroyed; that it is anything but waste to create needless public projects; that it is dangerous to let idle hordes of men return to work; that machines which increase the production of wealth and economic human effort are to be dreaded; that obstructions to free production and free consumption increase wealth; that a nation grows richer by forcing other nations to take its goods for less than they cost to produce; that saving is stupid or wicked and that dissipation brings prosperity.
“What is prudence in the conduct of every private family,” said Adam Smith’s strong common sense in reply to the sophists of his time, “can scarce be folly in that of a great kingdom.” But lesser men get lost in complications. They do not re-examine their reasoning even when they emerge with conclusions that are palpably absurd…. It is certainly true, however, that a little economics can easily lead to the paradoxical and preposterous conclusions we have just rehearsed, but that depth in economics brings men back to common sense.