The knowledge of the circumstances of which we must make use never exists in concentrated or integrated form, but solely as the dispersed bits of incomplete and frequently contradictory knowledge which all the separate individuals possess.
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.
