I am thinking about something much more important than bombs. I am thinking about computers.

Technological possibilities are irresistible to man. If man can go to the moon, he will. If he can control the climate, he will.

I would like to make a confession which may seem immoral: I do not believe absolutely in Hilbert space any more.

There is no point in being precise if you do not even know what you are talking about.

Neumann, to a physicist seeking help with a difficult problem: Simple. This can be solved by using the method of characteristics. Physicist: I'm afraid I don't understand the method of characteristics. Neumann: In mathematics you don't understand things. You just get used to them.

Science, as well as technology, will in the near and in the farther future increasingly turn from problems of intensity, substance, and energy, to problems of structure, organization, information, and control.

Truth is much too complicated to allow anything but approximations.