A lot of opportunities in life tend to last a short while, due to some temporary inefficiency... For each of us, really good investment opportunities aren't going to come along too often and won't last too long, so you've got to be ready to act and have a prepared mind.

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

Acknowledging what you don't know is the dawning of wisdom.

A few public hangings will really change behavior. One of our Presidents said if he could execute three people each year for no cause, it would make it a lot easier to govern. When someone said that's not enough, he said, "Oh yes it is, because I'd publish the list of people under consideration."

A lot of share-buying, not bargain-seeking, is designed to prop stock prices up. Thirty to 40 years ago, it was very profitable to look at companies that were aggressively buying their own shares. They were motivated simply to buy below what it was worth.

Black-Scholes is a know-nothing system. If you know nothing about value - only price - then Black-Scholes is a pretty good guess at what a 90-day option might be worth. But the minute you get into longer periods of time, it's crazy to get into Black-Scholes. For example, at Costco we issued stock options with strike prices of $30 and $60, and Black-Scholes valued the $60 ones higher. This is insane.

Intense interest in any subject is indispensable if you're really going to excel in it.