I'm sure we would not have had men on the Moon if it had not been for Wells and Verne and the people who write about this and made people think about it. I'm rather proud of the fact that I know several astronauts who became astronauts through reading my books.

Religion is a by-product of fear. For much of human history it may have been a necessary evil, but why was it more evil than necessary? Isn’t killing people in the name of god a pretty good definition of insanity?

Don't mess up the environment until you're quite sure what you're doing.

We stand now at the turning point between two eras. Behind us is a past to which we can never return... The coming of the rocket brought to an end a million years of isolation... the childhood of our race was over and history as we know it began.

It has yet to be proven that intelligence has any survival value.

The moment when one first meets a great work of art has an impact that can never again be recaptured.

The creation of wealth is certainly not to be despised, but in the long run the only human activities really worthwhile are the search for knowledge, and the creation of beauty. This is beyond argument, the only point of debate is which comes first.