There's no way that you can live an adequate life without making many mistakes.

Berkshire's past record has been almost ridiculous. If Berkshirehad used even half the leverage of, say, Rupert Murdoch, it would be five times its current size.

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.

If the technology hadn't changed, they [newspapers] would still be great businesses. Network TV [in its heyday], anyone could run and do well. If Tom Murphy as running it, you'd do very well, but even your idiot nephew could do well. Fortunately, carbide cutting tools [such as those made by Iscar] don't have these types of substitutes.

An idea or a fact is not worth more merely because it's more available to you.

The possibility that stock value in aggregate can become irrationally high is contrary to the hard-form "efficient market" theory that many of you once learned as gospel from your mistaken professors of yore. Your mistaken professors were too much influenced by "rational man" models of human behavior from economics and too little by "foolish man" models from psychology and real-world experience.

Size will hurt returns. Look at Berkshire Hathaway - the last five things Warren has done have generated returns that are splendid by historical standards, but now give him $100 billion in assets and measure outcomes across all of it, it doesn't look so good. We can only buy big positions, and the only time we can get big positions is during a horrible period of decline or stasis. That really doesn't happen very often.