Spacemen - men who work in space, pilots and jetmen and astrogators and such - are men who like a few million miles of elbow room.

No statement should be believed because it is made by an authority.

My old man claimed that the more complicated the law the more opportunity for scoundrels.

I think that science fiction has a distinct therapeutic value because all of it has as its primary postulate that the world does change. I cannot overemphasize the importance of that idea.

On two subjects the overwhelming majority of people regarded their own opinions as Absolute Truth, and sincerely believed that anyone who disagreed with them was immoral, outrageous, sinful, sacrilegious, offensive, intolerable, stupid, illogical, treasonable, actionable, against the public interest, ridiculous, and obscene. The two subjects were (of course) sex and religion.

Formal courtesy between husband and wife is even more important than it is between strangers.

When railroading time comes you can railroad—but not before.