A lot of scientists act on their beliefs and so do things that look crazy to the rest of us.

The invisible hand never picks up the check.

Life is insanely robust, though we can make species go extinct, and this is the bad thing. So I always make the point that you can't say, 'Is it too late?' That is the terrible question, because either answer promotes inaction. If it's too late, you don't need to act; if it's not too late, you don't need to act.

It was a world of acts, and words had no more influence on acts than the sound of a waterfall has on the flow of the stream.

Sad but true: individual intelligence probably peaked in the Upper Paleolithic, and we have been self-domesticated creatures ever since

You can never properly predict the future as it really turns out. So you are doing something a little different when you write science fiction. You are trying to take a different perspective on now.

It was a mistake to speak one's mind at any time, unless it perfectly matched your political purpose; and it never did.