The only way to define your limits is by going beyond them.

Mars is the next frontier, what the Wild West was, what America was 500 years ago. It's time to strike out anew....Mars is where the action is for the next thousand years....The characteristic of human nature, and perhaps our simian branch of the family, is curiosity and exploration. When we stop doing that, we won't be humans anymore. I've seen far more in my lifetime than I ever dreamed. Many of our problems on Earth can only be solved by space technology....The next step is in space. It's inevitable.

I doubt if there is a single field of study so theoretical, so remote from what is laughingly called everyday life, that it may not one day produce something that will shake the world.

I'm quite fond of the writer who told a beginning author, "If you've got a message, use Western Union."

You don't believe in organized religion, yet a major theme in so many of your works seems to be a quest for God.

Getting information from the internet is like getting a glass of water from the Niagara Falls.

The time was fast approaching when Earth, like all mothers, must say farewell to her children.