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.

If man can live in Manhattan, he can live anywhere.

Astronomy, as nothing else can do, teaches men humility.

Why, Robert Singh often wondered, did we give our hearts to friends whose life spans are so much shorter than our own?

It is really quite amazing by what margins competent but conservative scientists and engineers can miss the mark, when they start with the preconceived idea that what they are investigating is impossible.

Training was one thing, reality another.

I will not be afraid because I understand ... And understanding is happiness.