The idea of caring is that someone is making money faster [than you are] is one of the deadly sins. Envy is a really stupid sin because it’s the only one you could never possibly have any fun at. There’s a lot of pain and no fun. Why would you want to get on that trolley?

And maybe the cereal makers by and large have learned to be less crazy about fighting for market share-because if you get even one person who's hell-bent on gaining market share.... For example, if I were Kellogg and I decided that I had to have 60% of the market, I think I could take most of the profit out of cereals. I'd ruin Kellogg in the process. But I think I could do it.

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.

Personally, I’ve gotten so that I now use a kind of two-track analysis. First, what are the factors that really govern the interests involved, rationally considered? And second, what are the subconscious influences where the brain at a subconscious level is automatically conclusions in various ways — which, by and large, are useful — but which often malfunction? One approach is rationality… And the other is to evaluate the psychological factors that cause subconscious conclusions — many of which are wrong.

We all are learning, modifying, or destroying ideas all the time. Rapid destruction of your ideas when the time is right is one of the most valuable qualities you can acquire. You must force yourself to consider arguments on the other side.

It's my guess that something like 5% of GDP goes to money management and itsattendant friction. I define it broadly - annuities, incentive pay, all trading, etc. Nobody else has used figures that high, but that's my guess. Worst of all, the people doing this are among the best and the brightest. Hundreds and thousands of engineers, etc. are going into hedge funds and investment banking. That is not an intelligent allocation of the brainpower of the civilization.

Go to bed smarter than when you woke up.