From award-winning science fiction author Larry Niven comes a list that describes, in his own words, "how the Universe works" — also known as "Niven's Laws." Said list has evolved over the years and as a result variations exist. The version below is quoted from the book, Take My Advice, published in 2007.
(Source: Take My Advice; Image: Larry Niven, via Wikipedia.)
To the best I've been able to tell in fifty years of observation, this is how the Universe works. I hope I didn't leave anything out.
1a. Never throw shit at an armed man.
1b. Never stand next to someone who is throwing shit at an armed man. You wouldn't think anyone would need to be told this. Does anyone remember the Democratic National Convention of 1968?
2. Never fire a laser at a mirror.
3. Mother Nature doesn't care if you're having fun. (Please note: You will not be stopped! There are things you can't do because your metabolism uses oxidation of sugar, or you're made of meat, or you're a mammal, or human. Funny chemicals will kill you slow or quick, or ruin your brain...or prolong your life, if you're careful. You can't fly like an eagle, nor yet like Daedalus, but you can fly with a hang glider, or ride through the sky in something like a cramped living room. There are even answers to jet lag. You can cheat. Nature doesn't care, but don't get caught.)
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. These remarks apply to individuals, nations, and civilizations. Notice that the constant k is different for every civilization and different for every individual.
5. Psi and/or magical powers, if real, are nearly useless. Over the lifetime of the human species we would otherwise have done something with them.
6. It is easier to destroy than create. If human beings didn't have a strong preference for creation, nothing would get built.
7. Any damn fool can predict the past. Generals are famous for this, and certain writers too.
8. History never repeats itself.
9. Ethics changes with technology.
10. Anarchy is the least stable of social structures. It falls apart at a touch.
11. There is a time and a place for tact. (And there are times when tact is entirely misplaced.)
12. The ways of being human are bound but infinite.
13. The world's dullest subjects, in order:
a. Somebody else's diet.
b. How to make money for a worthy cause.
c. Special-Interest Liberation.
14. 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 need not be one of them.
15. Niven's Law for Musicians: If the applause wasn't louder than the music, something's wrong. Play better or softer.
16. Fuzzy Pink Niven's Law: Never waste calories. Potato chips, candy, or hot fudge sundae consumption may involve you, your doctor, your wardrobe, and other factors. But Fuzzy Pink's Law implies:
Don't eat soggy potato chips.
Or cheap candy.
Or an inferior hot fudge sundae.
Or a cold soggy pizza.
17. There is no cause so right that one cannot find a fool following it. This one's worth noticing. At the first High Frontier Convention, the minds assembled were among the best in the world, and I couldn't find a conversation that didn't teach me something. But the only newspersons I ran across were interviewing the only handicapped person among us. To prove a point, one may seek out a foolish communist, thirteenth-century liberal, Scientologist, High Frontier advocate, Mensa member, science fiction fan, gamer, Christian, or fanatical devotee of Special-Interest Lib--but that doesn't really reflect on the cause itself. Ad hominem arguments save time, but it's still a fallacy.
18. No technique works if it isn't used. If that sounds simplistic, look at some specifics: Telling friends about your diet won't make you thin. Buying a diet cookbook won't either. Even reading the recipes won't do it. Knowing about Alcoholics Anonymous, looking up the phone number, even jotting it on real paper, won't make you sober. Buying weights doesn't give you muscles. Signing a piece of paper won't make missiles disappear, even if you make lots of copies and tell every anchorperson on earth. Endlessly studying designs for spacecraft won't put anything into orbit. And so forth. But you surely know someone who tried it that way, and maybe you're one yourself.
19. Not responsible for advice not taken.