No one can possibly have lived through the Great Depression without being scarred by it. No amount of experience since the depression can convince someone who has lived through it that the world is safe economically.

God, how that stings! I've spent a lifetime loving science fiction and now I find that you must expect nothing of something that's just science fiction.

Maybe happiness is this: not feeling like you should be elsewhere, doing something else, being someone else.

When asked for advice by beginners. Know your ending, I say, or the river of your story may finally sink into the desert sands and never reach the sea.

To surrender to ignorance and call it God has always been premature, and it remains premature today.

A scientist is as weak and human as any man, but the pursuit of science may ennoble him even against his will.

Intelligence is a valuable thing, but it is not usually the key to survival. Sheer fecundity ... usually counts. The intelligent gorilla doesn't do as well as the less intelligent but more-fecund rat, which doesn't do as well as the still-less-intelligent but still-more-fecund cockroach, which doesn't do as well as the minimally-intelligent but maximally-fecund bacterium.