"1. a.Never throw shit at an armed man. b.Never stand next to someone who is throwing shit at an armed man. 2.Never fire a laser at a mirror. 3.Moth… - Larry Niven

"1. a.Never throw shit at an armed man.
b.Never stand next to someone who
is throwing shit at an armed man.

2.Never fire a laser at a mirror.
3.Mother Nature doesn't care if you're having fun.
4.F × S = k. The product of Freedom and Security is a constant. To gain more freedom of thought and/or action, you must give up some security, and vice versa.
5.Psi and/or magical powers, if real, are nearly useless.
6.It is easier to destroy than create.
7.Any damn fool can predict the past.
8.History never repeats itself.
9.Ethics change with technology.
10.There Ain't No Justice. (often abbreviated to TANJ)
11.Anarchy is the least stable of social structures. It falls apart at a touch.
12.There is a time and place for tact. And there are times when tact is entirely misplaced.
13.The ways of being human are bounded but infinite.
14.The world's dullest subjects, in order:
a.Somebody else's diet.
b.How to make money for a worthy cause.
c.The Kardashians.

15.The only universal message in science fiction: There exist minds that think as well as you do, but differently.
Niven's corollary: The gene-tampered turkey you're talking to isn't necessarily one of them.
16.Fuzzy Pink Niven's Law: Never waste calories.
17.There is no cause so right that one cannot find a fool following it.
in variant form in Fallen Angels as "Niven's Law: No cause is so noble that it won't attract fuggheads."
18.No technique works if it isn't used.
19.Not responsible for advice not taken.
20.Old age is not for sissies."