After years of finding mathematics easy, I finally reached integral calculus and came up against a barrier. I realized that this was as far as I could go, and to this day I have never successfully gone beyond it in any but the most superficial way.

What lasts in the reader's mind is not the phrase but the effect the phrase created: laughter, tears, pain, joy. If the phrase is not affecting the reader, what's it doing there? Make it do its job or cut it without mercy or remorse.

Science is a set of rules to keep us from telling lies to each other. All scientists really have is a reputation for telling the truth.

To introduce something altogether new would mean to begin all over, to become ignorant again, and to run the old, old risk of failing to learn.

Oh, for a pin that would puncture pretension!

On Earth, we are unmanned by our longing for a pastoral past that never really existed; and that, if it had existed, could never exist again...on the Moon, there is no past to long for or dream about. There is no direction but forward.

Why continue? Because we must. Because we have the call. Because it is nobler to fight for rationality without winning than to give up in the face of continued defeats. Because whatever true progress humanity makes is through the rationality of the occasional individual and because any one individual we may win for the cause may do more for humanity than a hundred thousand who hug their superstitions to their breast.