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

Although I am very interested in the subject of human misjudgment - and lord knows I've created a good bit of it - I don't think I've created my full statistical share, and I think that one of the reasons was I tried to do something about this terrible ignorance I left the Harvard Law School with.

Intelligent people make decisions based on opportunity costs.

If you can buy the best companies, over time the pricing takes care of itself.

Of course I'm troubled by huge consumer debt levels - we've pushed consumer credit very hard in the US. Eventually, if it keeps growing, it will stop growing. As Herb Stein said, "If something cannot go on forever, it will stop." When it stops, it may be unpleasant. Other than Herb Stein's quote, I have no comment. But the things that trouble you are troubling me.

A lot of share-buying, not bargain-seeking, is designed to prop stock prices up. Thirty to 40 years ago, it was very profitable to look at companies that were aggressively buying their own shares. They were motivated simply to buy below what it was worth.

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.