[The historical] development in the international system may almost be defined as the process by which we pass from stable war to stable peace.

I have been gradually coming under the conviction, disturbing for a professional theorist, that there is no such thing as economics - there is only social science applied to economic problems.

The only religion that still demands human sacrifice is nationalism.

Physicists only talk to physicists, economists to economists-worse still, nuclear physicists only talk to nuclear physicists and econometricians to econometricians. One wonders sometimes if science will not grind to a stop in an assemblage of walled-in hermits, each mumbling to himself words in a private language that only he can understand.

We should always bear in mind that numbers represent a simplification of reality.

We make our tools, and then they shape us.

[on the theory of the firm] It is exactly analogous to the analysis of the reactions of a consumer by means of indifferent curves. Indeed, a consumer is merely a 'firm' whose product is 'utility.'