If you aren't willing to own a stock for ten years, don't even think about owning it for ten minutes. Put together a portfolio of companies whose aggregate earnings march upward over the years, and so also will the portfolio's market value.

It's good to learn from your mistakes. It's better to learn from other people's mistakes.

[The U.S. Treasury] can borrow basically unlimited amounts. They can stay there for years and years. These assets will be worth more money over time. So when Merrill Lynch sells a bunch of mortgage-related assets at 22 cents on the dollar like they did a month or so ago, the buyer goes - is going to make money, and he's going to make a lot more money if it happens to be an institution like the U.S. government which has very, very cheap borrowing costs.

It is obvious that the performance of a stock last year or last month is no reason, per se, to either own it or to not own it now. It is obvious that an inability to "get even" in a security that has declined is of no importance. It is obvious that the inner warm glow that results from having held a winner last year is of no importance in making a decision as to whether it belongs in an optimum portfolio this year.

The advice "you never go broke taking a profit" is foolish.

The commission of the investment sins listed above is not limited to 'the little guy.' Huge institutional investors, viewed as a group, have long underperformed the unsophisticated index-fund investor who simply sits tight for decades. A major reason has been fees: Many institutions pay substantial sums to consultants who, in turn, recommend high-fee managers. And that is a fool's game.

Would you rather be the world's greatest lover, but have everyone think you're the world's worst lover? Or would you rather be the world's worst lover but have everyone think you're the world's greatest lover? Now, that's an interesting question.