Finding a single investment that will return 20% per year for 40 years tends to happen only in dreamland. In the real world, you uncover an opportunity, and then you compare other opportunities with that. And you only invest in the most attractive opportunities. That's your opportunity cost. That's what you learn in freshman economics. The game hasn't changed at all. That's why Modern Portfolio Theory is so asinine.

It is way less certain to be a wonderful business in the future. The threat is alternative mediums of information. Every newspaper is scrambling to parlay their existing advantage into dominance on the Internet. But it is way less sure [that this will occur] than the certainty 20 years ago that the basic business would grow steadily, so there's more downside risk. The perfectly fabulous economics of this business could become grievously impaired.

Over the long term, it's hard for a stock to earn a much better return that the business which underlies it earns. If the business earns six percent on capital over forty years and you hold it for that forty years, you're not going to make much different than a six percent return - even if you originally buy it at a huge discount. Conversely, if a business earns eighteen percent on capital over twenty or thirty years, even if you pay an expensive looking price, you'll end up with one hell of a result.

In my whole life, I have known no wise people (over a broad subject matter area) who didn't read all the time - none, zero. You'd be amazed at how much Warren reads - at how much I read. My children laugh at me. They think I'm a book with a couple of legs sticking out.

... some important factor doesn't lose its "share of force" just because some "expert" can better measure other types of force.

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.

Some years ago one oil company bought a fertilizer company, and every other major oil company practically ran out and bought a fertilizer company. And there was no more damned reason for all these oil companies to buy fertilizer companies, but they didn't know exactly what to do, and if Exxon was doing it, it was good enough for Mobil and vice versa.