Never underestimate the power of human stupidity.

Everything is theoretically impossible, until it is done.

Women and cats will do as they please, and men and dogs should relax and get used to the idea.

An armed society is a polite society. Manners are good when one may have to back up his acts with his life.

I am free because I know that I alone am morally responsible for everything I do. I am free, no matter what rules surround me. If I find them tolerable, I tolerate them; if I find them too obnoxious, I break them. I am free because I know that I alone am morally responsible for everything I do.

Love is that condition in which the happiness of another person is essential to your own... Jealousy is a disease, love is a healthy condition. The immature mind often mistakes one for the other, or assumes that the greater the love, the greater the jealousy.

May you live as long as you wish and love as long as you live.

I never learned from a man who agreed with me.

One man's 'magic' is another man's engineering. 'Supernatural' is a null word.

Don't handicap your children by making their lives easy.

You can have peace. Or you can have freedom. Don't ever count on having both at once.

Political tags - such as royalist, communist, democrat, populist, fascist, liberal, conservative, and so forth - are never basic criteria. The human race divides politically into those who want people to be controlled and those who have no such desire.

When any government, or any church for that matter, undertakes to say to its subjects, This you may not read, this you must not see, this you are forbidden to know, the end result is tyranny and oppression no matter how holy the motives.

A competent and self-confident person is incapable of jealousy in anything. Jealousy is invariably a symptom of neurotic insecurity.

Be wary of strong drink. It can make you shoot at tax collectors... and miss.

Yield to temptation. It may not pass your way again.

Don't ever become a pessimist... a pessimist is correct oftener than an optimist, but an optimist has more fun, and neither can stop the march of events.

They didn't want it good, they wanted it Wednesday.

One man's theology is another man's belly laugh.

A society that gets rid of all its troublemakers goes downhill.

Being right too soon is socially unacceptable.

The difference between science and the fuzzy subjects is that science requires reasoning while those other subjects merely require scholarship.

Theology is never any help; it is searching in a dark cellar at midnight for a black cat that isn't there. Theologians can persuade themselves of anything.

When a place gets crowded enough to require ID's, social collapse is not far away. It is time to go elsewhere. The best thing about space travel is that it made it possible to go elsewhere.

The supreme irony of life is that hardly anyone gets out of it alive.

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

Sex without love is merely healthy exercise.

I don't see how an article of clothing can be indecent. A person, yes.

One of the sanest, surest, and most generous joys of life comes from being happy over the good fortune of others.

There is no way that writers can be tamed and rendered civilized or even cured. The only solution known to science is to provide the patient with an isolation room, where he can endure the acute stages in private and where food can be poked in to him with a stick.

Anyone who considers protocol unimportant has never dealt with a cat.

One could write a history of science in reverse by assembling the solemn pronouncements of highest authority about what could not be done and could never happen.

Never insult anyone by accident.

For me, politeness is a sine qua non of civilization.

It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so.

By cultivating the beautiful we scatter the seeds of heavenly flowers, as by doing good we cultivate those that belong to humanity.

The universe never did make sense; I suspect it was built on government contract.

It's an indulgence to sit in a room and discuss your beliefs as if they were a juicy piece of gossip.

Writing is not necessarily something to be ashamed of, but do it in private and wash your hands afterwards.

Never worry about theory as long as the machinery does what it's supposed to do.

To be matter-of-fact about the world is to blunder into fantasy - and dull fantasy at that, as the real world is strange and wonderful.