Civilization will reach maturity only when it learns to value diversity of character and of ideas.

There is a special sadness in achievement, in the knowledge that a long-desired goal has been attained at last, and that life must now be shaped toward new ends.

There is hopeful symbolism in the fact that flags do not wave in a vacuum.

My objection to organized religion is the premature conclusion to ultimate truth that it represents.

Science fiction does not attempt to predict. It extrapolates. It just says, "What if?" not what will be? Because you can never predict what will happen, particularly in politics and economics. You can to some extent predict in the technological sphere - flying, space travel, but even there we missed badly on some things, like computers. No one imagined the incredible impact of computers, even though robot brains of various kinds but the idea that one day every house would have a computer in every room and that one day we'd have computers built into our clothing, nobody ever thought of that.

The dinosaurs disappeared because they could not adapt to their changing environment. We shall disappear if we cannot adapt to an environment that now contains spaceships, computers - and thermonuclear weapons.

Judge me by my deeds, though they are few, rather than my words, though they are many.