[GEICO] got to thinking that, because they were making a lot of money, they knew everything. And they suffered huge losses. All they had to do was to cut out all the folly and go back to the perfectly wonderful business that was lying there.

Missing out on some opportunity never bothers us. What's wrong with someone getting a little richer than you? It's crazy to worry about this.

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.

Beta and modern portfolio theory and the like - none of it makes any sense to me.

I think we have lost our way when people like the [board of] governors and the CEO of the NYSE fail to realize they have a duty to the rest of us to act as exemplars... You do not want your first-grade school teacher to be fornicating on the floor or drinking booze in the classroom; similarly you do not want your stock exchange to be setting the wrong moral example.

People calculate too much and think too little.

Almost all good businesses engage in 'pain today, gain tomorrow' activities.