What good is envy? It’s the one sin you can’t have any fun at.

The idea of excessive diversification is madness. Wide diversification, which necessarily includes investment in mediocre businesses, only guarantees ordinary results.

You've got to have models in your head and you've got to array you experience - both vicarious and direct - onto this latticework of mental models.

In Gillette's case, they keep surfing along new technology which is fairly simple by the standards of microchips. But it's hard for competitors to do. So they've been able to stay constantly near the edge of improvements in shaving.

[With] closet indexing....you're paying a manager a fortune and he has 85% of his assets invested parallel to the indexes. If you have such a system, you're being played for a sucker.

When you borrow a man's car, always return it with a tank of gas.

The Internet bubble circa 2000 is the most extreme in modern capitalism. In the 1930s, we had the worst depression in 600 years. Today is almost as extreme in the opposite way.