The best thing about space travel is that it made it possible to go elsewhere.

Budget the luxuries first.

Almost everything about a human creature is ridiculous, except its ability to suffer bravely and die gallantly for whatever it loves and believes in. The validity of that belief, the appropriateness of that love, is irrelevant; it is the bravery and the gallantry that count.

Being generous is inborn; being altruistic is a learned perversity. No resemblance --

Social responsibility above the level of family, or at most of tribe, requires imagination-- devotion, loyalty, all the higher virtues -- which a man must develop himself; if he has them forced down him, he will vomit them out.

The hardest part of gaining any new idea is sweeping out the false idea occupying that niche.

Never pick up a stray kitten . . . unless you've already made up your mind to be owned by it.