The most important thing about Spaceship Earth - an instruction book didn't come with it.

One outstandingly important fact regarding Spaceship Earth, and that is that no instruction book came with it.

Spaceship Earth: The problem for the passengers is that there is no manual to identify all the parts, and no instructions on how to operate the spaceship.

Controlled time is our true wealth.

Dictators never invent their own opportunities.

When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong.