I’m struck again by the irony that spaceflight-conceived in the cauldron of nationalist rivalries and hatreds-brings with it a stunning transnational vision. You spend even a little time contemplating the Earth from orbit and the most deeply engrained nationalisms begin to erode. They seem the squabbles of mites on a plum.

The difference between physics and metaphysics is not that the practitioners of one are smarter than the practitioners of the other. The difference is that the metaphysicist has no laboratory.

Absolute certainty will always elude us. We will always be mired in error. The most each generation can hope for is to reduce the error. . . .

It is said that men may not be the dreams of the god, but rather that the gods are the dreams of men.

I can find in my undergraduate classes, bright students who do not know that the stars rise and set at night, or even that the Sun is a star.

What does it mean for a civilisation to be a million years old? We have had radio telescopes and spaceships for a few decades; our technical civilisation is a few hundred years old ... an advanced civilisation millions of years old is as much beyond us as we are beyond a bushbaby or a macaque

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand. It has been said that astronomy is a humbling and character-building experience..... To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.