Nothing gives life more zest that running for your life.

It may take endless wars and unbearable population pressure to force-feed a technology to the point where it can cope with space. In the universe, space travel may be the normal birth pangs of an otherwise dying race. A test. Some races pass, some fail.

Geniuses and supergeniuses always make their own rules about sex as on everything else; they do not accept the monkey customs of their lessers.

A fool cannot be protected from his folly. If you attempt to do so, you will not only arouse his animosity but also you will be attempting to deprive him of whatever benefit he is capable of deriving from experience. Never attempt to teach a pig to sing; it wastes your time and annoys the pig.

You can sway a thousand men by appealing to their prejudices quicker than you can convince one man by logic.

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

A family reunion is an effective form of birth control.