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 slaves of some defunct economist.

A study of the history of opinion is a necessary preliminary to the emancipation of the mind.

The difficulty lies not so much in developing new ideas as in escaping the old ones.

The biggest problem is not to let people accept new ideas, but to let them forget the old ones.

It is ideas, not vested interests, which are dangerous for good or evil.

I am sure that the power of vested interests is vastly exaggerated compared with the gradual encroachment of ideas.

The idea behind stamped money is sound.