After nearly making a terrible mistake not buying See's, we've made this mistake many times. We are apparently slow learners. These opportunity costs don't show up on financial statements, but have cost us many billions.

We believe that almost all really good investment records will involve relatively little diversification. The basic idea that it was hard to find good investments and that you wanted to be in good investments, and therefore, you'd just find a few of them that you knew a lot about and concentrate on those seemed to me such an obviously good idea. And indeed, it's proven to be an obviously good idea. Yet 98% of the investing world doesn't follow it. That's been good for us.

Whoever makes you smarter a little earlier in life makes you better

People like the robber barons assumed that the doctrine of the survival of the fittest authenticated them as deserving power. You know, "I'm the richest. Therefore, I'm the best. God's in his heaven, etc." And that reaction of the robber barons was so irritating to people that it made it unfashionable to think of an economy as an ecosystem. But the truth is that it is a lot like an ecosystem. And you get many of the same results.

I have what I call an iron prescription that helps me keep sane when I naturally drift toward preferring one ideology over another and that is: I say that I'm not entitled to have an opinion on this subject unless I can state the arguments against my position better than the people who support it. I think only when I've reached that state am I qualified to speak. This business of not drifting into extreme ideology is a very, very important thing in life

We don't have any miraculous way of avoiding taxes at Wesco and Berkshire.

Suppose you were a real estate investor with a 1/3 interest in the best apartment complex in town, the best mall, and the best office building. Would you feel like a poor, undiversified investor? No! But as soon as you get into stocks, people feel this way. Partly, people need to justify their fees.