From the Pittsburgh Tribune-Review:

By Donald J. Boudreaux
Saturday, June 21, 2008

At the end of a famous book filled with a good deal of infamous nonsense, John Maynard Keynes observed — I believe correctly — that:

” … the ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood. Indeed the world is ruled by little else. Practical men, who believe themselves to be quite exempt from any intellectual influence, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back. I am sure that the power of vested interests is vastly exaggerated compared with the gradual encroachment of ideas.”