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.

By investing at a discount, Benjamin Graham knew that he was unlikely to experience losses.

The risk of an investment is described by both the probability and the potential amount of loss. The risk of an investment-the probability of an adverse outcome-is partly inherent in its very nature. A dollar spent on biotechnology research is a riskier investment than a dollar used to purchase utility equipment. The former has both a greater probability of loss and a greater percentage of the investment at stake.

You need humility to say 'I might be wrong.'

It sounds kind of crazy, but in times of turmoil in the market, I've felt a sort of serenity in knowing that I've checked and re-checked my work, one plus one still equals two regardless of where a stock trades right after I buy it.

There is no amount of bad news that the markets cannot see past.

The government - the ultimate short-term-oriented player - cannot withstand much pain in the economy or the financial markets. Bailouts and rescues are likely to occur, though not with sufficient predictability for investors to comfortably take advantage. The government will take enormous risks in such interventions, especially if the expenses can be conveniently deferred to the future. Some of the price-tag is in the form of back- stops and guarantees, whose cost is almost impossible to determine.