The numbers of distinct human societies or nations, when our race is twice its present age, may be far greater than the total number of all the men who have ever lived up to the present time.

It is vital to remember that information - in the sense of raw data - is not knowledge, that knowledge is not wisdom, and that wisdom is not foresight. But information is the first essential step to all of these.

I don't believe in God but I'm very interested in her.

Some dangers are so spectacular and so much beyond normal experience that the mind refuses to accept them as real, and watches the approach of doom without any sense of apprehension. The man who looks at the onrushing tidal wave, the descending avalanche, or the spinning funnel of the tornado, yet makes no attempt to flee, is not necessarily paralyzed with fright or resigned to an unavoidable fate. He may simply be unable to believe that the message of his eyes concerns him personally. It is all happening to somebody else.

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

I have never grown up, but I will never stop growing.

There's no real objection to escapism, in the right places... We all want to escape occasionally. But science fiction is often very far from escapism, in fact you might say that science fiction is escape into reality... It's a fiction which does concern itself with real issues: the origin of man; our future. In fact I can't think of any form of literature which is more concerned with real issues, reality.