...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 influences, 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.

- John Maynard Keynes (1935)