If you get into the mental habit of relating what you're reading to the basic structure of the underlying ideas being demonstrated, you gradually accumulate some wisdom.

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.

Over the long term, the eclipse rate of great civilizations being overtaken is 100%. So you know how it's going to end. (Laughter) I'm more optimistic about the staying power of what's good in this country. But just because you have a wonderful spouse doesn't mean you should treat her badly. You have the feeling that some of the old virtues [that made this country great] are lessening. But there's so much good and so much strength left that I would not expect this country to suddenly founder.

At most corporations if you make an acquisition and it turns out to be a disaster, all the paperwork and presentations that caused the dumb acquisition to be made are quickly forgotten. You've got denial, you've got everything in the world. You've got Pavlovian association tendency. Nobody even wants to even be associated with the damned thing or even mention it. At Johnson & Johnson, they make everybody revisit their old acquisitions and wade through the presentations. That is a very smart thing to do. And by the way, I do the same thing routinely.

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.

You'll better understand the evil when top audit firms started selling fraudulent tax shelters when I tell you that one told me that they're better [than the others] because they only sold [the schemes] to their top-20 clients, so no-one would notice.

Obviously, consideration of costs is key, including opportunity costs. Of course capital isn't free. It's easy to figure out your cost of borrowing, but theorists went bonkers on the cost of equity capital. They say that if you're generating a 100% return on capital, then you shouldn't invest in something that generates an 80% return on capital. It's crazy.