If you have competence, you know the edge. It wouldnt be a competence if you didnt know where the boundaries lie. Asking whether youve passed the boundary is a question that almost answers itself.

I believe in the discipline of mastering the best that other people have ever figured out. I don't believe in just sitting down and trying to dream it all up yourself. Nobody's that smart.

We tend to buy things - a lot of things - where we don't know exactly what will happen, but the outcome will be decent.

[In picking stocks] You really have to know a lot about business. You have to know a lot about competitive advantage. You have to know a lot about the maintainability of competitive advantage. You have to have a mind that quantifies things in terms of value. And you have to be able to compare those values with other values available in the stock market.

The beauty of a financial institution is that there are a lot of ways to go to hell in a bucket. You can push credit too far, do a dumb acquisition, leverage yourself excessively - it's not just derivatives [that can bring about your downfall].

Wrigley is a great business, but that doesn't solve the problem. Buying great businesses at advantageous prices is very tough.

Even bright people are going to have limited, really valuable insights in a very competitive world when they're fighting against other very bright, hardworking people. And it makes sense to load up on the very few good insights you have instead of pretending to know everything about everything at all times.