Unlike return, however, risk is no more quantifiable at the end of an investment that it was at its beginning. Risk simply cannot be described by a single number. Intuitively we understand that risk varies from investment to investment: a government bond is not as risky as the stock of a high-technology company. But investments do not provide information about their risks the way food packages provide nutritional data.

While knowing how to value businesses is essential for investment success, the first and perhaps most important step in the investment process is knowing where to look for opportunities

Almost every financial blow up is because of leverage.

It is important to remember that value investing is not a perfect science. It is an, with an ongoing need for judgment, refinement, patience, and reflection. It requires endless curiosity, the relentless pursuit of additional information, the raising of questions, and the search for answers. It necessitates dealing with imperfect information - knowing you will never know everything and that that must not prevent you from acting. It requires a precarious balance between conviction, steadfastness in the face of adversity, and doubt - keeping in mind the possibility that you could be wrong.

While no one wishes to incur losses, you couldn't prove it from an examination of the behavior of most investors and speculators. The speculative urge that lies within most of us is strong; the prospect of a free lunch can be compelling, especially when others have already seemingly partaken. It can be hard to concentrate on potential losses while others are greedily reaching for gains and your broker is on the phone offering shares in the latest "hot" initial public offering. Yet the avoidance of loss is the surest way to ensure a profitable outcome.

Investing is the intersection of economics and psychology. The analysis is actually the easy part. The economics, the valuation of the business isn't that hard. The psychology - how much do you buy, do you buy it at this price, do you wait for a lower price, what do you do when it looks like the world might end - those things are harder. Knowing whether you stand there, buy more, or whether something has legitimately gone wrong and you need to sell, those are harder things. That you learn with experience, by having the right psychological makeup.

Value investors will not invest in businesses that they cannot readily understand or ones they find excessively risky. Hence few value investors will own the shares of technology companies. Many also shun commercial banks, which they consider to have unanalyzable assets, as well as property and casualty insurance companies, which have both unanalyzable assets and liabilities.