Science fiction seldom attempts to predict the future. More often than not, it tries to prevent the future.

Death focuses the mind on the things that really matter: why are we here, and what should we do?

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.

Any path to knowledge is a path to God-or Reality, whichever word one prefers to use

I've been saying for a long time that I'm hoping to find intelligent life in Washington.

I am an optimist. Anyone interested in the future has to be otherwise he would simply shoot himself.

Behind every man now alive stand thirty ghosts, for that is the ratio by which the dead outnumber the living.