As his body became more and more defenseless, so his means of offense became steadily more frightful.

As three laws were good enough for Newton, I have modestly decided to stop there.

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

When I start on a book, I have been thinking about it and making occasional notes for some time... So I have lots of theme, locale, subjects and technical ideas... I don't worry about long periods of not doing anything. I know my subconscious is busy.

We stand now at the turning point between two eras. Behind us is a past to which we can never return... The coming of the rocket brought to an end a million years of isolation... the childhood of our race was over and history as we know it began.

Across the gulf of centuries, the blind smile of Homer is turned upon our age. Along the echoing corridors of time, the roar of the rockets merges now with the creak of the wind-taut rigging. For somewhere in the world today, still unconscious of his destiny, walks the boy who will be the first Odysseus of the Age of Space.

I would defend the liberty of consenting adult creationists to practice whatever intellectual perversions they like in the privacy of their own homes; but it is also necessary to protect the young and innocent.