These days there seems to be nowhere left to explore, at least on the land area of the Earth. Victims of their very success, the explorers now pretty much stay home.

Except for fools and madmen, everyone knows that nuclear war would he an unprecedented human catastrophe.

A blade of grass is a commonplace on Earth; it would be a miracle on Mars. Our descendants on Mars will know the value of a patch of green. And if a blade of grass is priceless, what is the value of a human being?

I believe that in every person is a kind of circuit which resonates to intellectual discovery-and the idea is to make that resonance work

Otherwise we don't run the government the government runs us

Extraordinary observations require extraordinary evidence to make them believable.

The visions we offer our children shape the future.