We tend to become like the worst in those we oppose.

Once men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them.

Then, as his planet killed him, it occurred to Kynes that his father and all the other scientists were wrong, that the most persistent principles of the universe were accident and error.

Every civilization must contend with an unconscious force which can block, betray, or countermand almost any conscious intention of the collectivity.

Clinging to any form of conservatism can be dangerous. Become too conservative and you are unprepared for surprises. You cannot depend on luck. Logic is blind and often knows only its own past. Logic is good for playing chess but is often too slow for the needs of survival.

A man is a fool not to put everything he has, at any given moment, into what he is creating.

There is in each of us an ancient force that takes and an ancient force that gives. A man finds little difficulty facing that place within himself where the taking force dwells, but it's almost impossible for him to see into the giving force without changing into something other than man. For a woman, the situation is reversed. ... These things are so ancient within us that they're ground into each separate cell of our bodies... It's as easy to be overwhelmed by giving as by taking.