You fix what can be fixed, and what can't be fixed you endure. - Charlie Munger

It's not the bad ideas that do you in, it’s the good ideas. And you may say, 'That can't be so. That's paradoxical. What he [Graham] meant was that if a thing is a bad idea, it’s hard to overdo. But where there is a good idea with a core of essential and important truth, you can’t ignore it. And then it's so easy to overdo it. So the good ideas are a wonderful way to suffer terribly if you overdo them

The first rule is that you can't really know anything if you just remember isolated facts and try and bang 'em back. If the facts don't hang together on a latticework of theory, you don't have them in a usable form.

It’s not possible for investors to consistently outperform the market. Therefore you’re best served investing in a diversified portfolio of low-cost index funds [or exchange-traded funds].