The choice, as Wells once said, is the Universe-or nothing. . . . The challenge of the great spaces between the worlds is a stupendous one; but if we fail to meet it, the story of our race will be drawing to its close. Humanity will have turned its back upon the still untrodden heights and will be descending again the long slope that stretches, across a thousand million years of time, down to the shores of the primeval sea.

In fact, one of the arguments for searching for intelligent life in space, elsewhere, is that we have no evidence that intelligence has any survival value. The most successful creatures on this planet are the cockroaches. They've been around, what is it, 100 million years or so and I suspect they'll still be there 100 million years in the future. Maybe intelligence is an evolutionary aberration which dooms its possessors in the way armor may have doomed some of the dinosaurs.

I sometimes wonder how we spent leisure time before satellite television and Internet came along…and then I realise that I have spent more than half of my life in the ‘dark ages’!

In all the universe there is nothing more precious than mind.

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

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.

The more wonderful the means of communication, the more trivial, tawdry, or depressing its contents seemed to be.