If the same family were always on the bottom, then you'd have big resentments. But if DuPonts go down and Pampered Chef up, [that's good]. That much churn makes people think the system is fairer. Buffett: We don't like churn now, but we liked it more 30-40 years ago.

Opportunity cost is a huge filter in life. If you've got two suitors who are really eager to have you and one is way the hell better than the other, you do not have to spend much time with the other. And that's the way we filter out buying opportunities.

If the same family were always on the bottom, then you'd have big resentments. But if DuPonts go down and Pampered Chef up, [that's good]. That much churn makes people think the system is fairer. Buffett: We don't like churn now, but we liked it more 30-40 years ago.

Financial institutions make us nervous when they're trying to do well.

I have a name for people who went to the extreme efficient market theory-which is "bonkers". It was an intellectually consistent theory that enabled them to do pretty mathematics. So I understand its seductiveness to people with large mathematical gifts. It just had a difficulty in that the fundamental assumption did not tie properly to reality.

We don't have an isolated group [of senior managers] surrounded by servants. Berkshire's headquarters is a tiny little suite. We just came back from Berkshire's board meeting; it had moved up to the board room of the Kiewit company and [it was so large and luxurious that] I felt uncomfortable.

The great lesson in microeconomics is to discriminate between when technology is going to help you and when it's going to kill you. And most people do not get this straight in their heads. But a fellow like Buffett does. For example, when we were in the textile business, which is a terrible commodity business, we were making low-end textiles-which are a real commodity product. And one day, the people came to Warren and said, "They've invented a new loom that we think will do twice as much work as our old ones."