Intense interest in any subject is indispensable if you're really going to excel in it.

You've got to have models in your head and you've got to array you experience - both vicarious and direct - onto this latticework of mental models.

You must value the business in order to value the stock.

We have a high moral responsibility to be rational

You don't have to have perfect wisdom to get very rich - just a bit better than average over a long period of time.

If you turn on the television, you'll find the mothers of the most obvious criminals that man could ever diagnose, and they all think their sons are innocent. That's simple psychological denial. The reality is too painful to bear, so you just distort it until it's bearable. We all do that to some extent, and it's a common psychological misjudgment that causes terrible problems.

[With] closet indexing....you're paying a manager a fortune and he has 85% of his assets invested parallel to the indexes. If you have such a system, you're being played for a sucker.