I have never written a book that didn't teach me far more than it taught my reader.

There is nothing frightening about an eternal dreamless sleep. Surely it is better than eternal torment in Hell and eternal boredom in Heaven.

They absorb carbon monoxide and carbon dioxide and give out oxygen. What could be more desirable? And they look good in the bargain. Stop chopping down the rain forests and plant more saplings, and we're on our way.

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.

I am not responsible for what other people think. I am responsible only for what I myself think, and I know what that is. No idea I've ever come up with has ever struck me as a divine revelation. Nothing I have ever observed leads me to think there is a God watching over me.

I have never, in all my life, not for one moment, been tempted toward religion of any kind. The fact is that I feel no spiritual void. I have my philosophy of life, which does not include any aspect of the supernatural and which I find totally satisfying. I am, in short, a rationalist and believe only that which reason tells me is so.

It is in meeting the great tests that mankind can most successfully rise to great heights. Out of danger and restless insecurity comes the force that pushes mankind to newer and loftier conquests.