The safest way to get what you want is to deserve what you want.

I talked to one accountant, a very nice fellow who I would have been glad to have his family marry into mine. He said, "What these other accounting firms have done is very unethical. The [tax avoidance scheme] works best if it's not found out [by the IRS], so we only give it to our best clients, not the rest, so it's unlikely to be discovered. So my firm is better than the others." [Laughter] I'm not kidding. And he was a perfectly nice man. People just follow the crowd...Their mind just drifts off in a ghastly way.

If you have competence, you know the edge. It wouldnt be a competence if you didnt know where the boundaries lie. Asking whether youve passed the boundary is a question that almost answers itself.

Bull markets go to people's heads. If you're a duck on a pond, and it's rising due to a downpour, you start going up in the world. But you think it's you, not the pond.

The possibility that stock value in aggregate can become irrationally high is contrary to the hard-form "efficient market" theory that many of you once learned as gospel from your mistaken professors of yore. Your mistaken professors were too much influenced by "rational man" models of human behavior from economics and too little by "foolish man" models from psychology and real-world experience.

It is an unfortunate fact that great and foolish excess can come into prices of common stocks in the aggregate. They are valued partly like bonds, based on roughly rational projections of use value in producing future cash. But they are also valued partly like Rembrandt paintings, purchased mostly because their prices have gone up, so far.

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