Organized common (or uncommon) sense -- very basic knowledge -- is an enormously powerful tool. There are huge dangers with computers. People calculate too much and think too little.

I find it quite useful to think of a free-market economy - or partly free market economy - as sort of the equivalent of an ecosystem. Just as animals flourish in niches, people who specialize in some narrow niche can do very well.

There's no way that you can live an adequate life without making many mistakes.

Berkshire's whole record has been achieved without paying one ounce of attention to the efficient market theory in its hard form. And not one ounce of attention to the descendants of that idea, which came out of academic economics and went into corporate finance and morphed into such obscenities as the capital asset pricing model, which we also paid no attention to. I think you'd have to believe in the tooth fairy to believe that you could easily outperform the market by seven-percentage points per annum just by investing in high volatility stocks.

An investment decision in the common stock of a company frequently involves a whole lot of factors interacting ... the one thing that causes the most trouble is when you combine a bunch of these together, you get this lollapalooza effect.

I think there's something to be said for developing the disposition to own stocks without fretting.

Failure to handle psychological denial is a common way for people to go broke: you have made an enormous commitment to something. You have poured effort and money in. And the more you put in, the more that the whole consistency principle makes you think, "Now it has to work. If I put in just a little more, then it will work."