Selling, in particular, can be a challenge; many investors are tempted to become more optimistic when a security is performing well. This temptation must be resisted; tax considerations aside, when a security reaches full valuation, there is no longer a reason to own it.

If an asset has cash flow or the likelihood of cash flow in the near term and is not purely dependment on what a future buyer might pay, then it's an investment. If an asset's value is totally dependent on the amount a future buyer might pay, then its purchase is speculation.

To value investors the concept of indexing is at best silly and at worst quite hazardous. Warren Buffett has observed that "in any sort of a contest - financial, mental or physical - it's an enormous advantage to have opponents who have been taught that it's useless to even try." I believe that over time value investors will outperform the market and that choosing to match it is both lazy and shortsighted.

Do not trust financial market risk models. Despite the predilection of some analysts to model the financial markets using sophisticated mathematics, the markets are governed by behavioral science, not physical science.

Ultimately, nothing should be more important to investors than the ability to sleep soundly at night.

Occasionally we are asked whether it would make sense to modify our investment strategy to perform better in today's financial climate. Our answer, as you might guess, is: No! It would be easyfor us to capitulate to the runaway bull market in growth and technology stocks. And foolhardy. And irresponsible. And unconscionable. It is always easiest to run with the herd; at times, it can take a deep reservoir of courage and conviction to stand apart from it. Yet distancing yourself from the crowd is an essential component of long-term investment success.

Risk is not inherent in an investment; it is always relative to the price paid. Uncertainty is not the same as risk. Indeed, when great uncertainty - such as in the fall of 2008 - drives securities prices to especially low levels, they often become less risky investments.