As in roulette, same is true of the stock trader, who will find that the expense of trading weights the dice heavily against him.

Most businesses change in character and quality over the years, sometimes for the better, perhaps more often for the worse. The investor need not watch his companies' performance like a hawk; but he should give it a good, hard look from time to time.

Successful investing professionals are disciplined and consistent and they think a great deal about what they do and how they do it.

Never buy a stock because it has gone up or sell one because it has gone down.

No matter how careful you are, the one risk no investor can ever eliminate is the risk of being wrong. Only by insisting on what Graham called the "margin of safety" - never overpaying, no matter how exciting an investment seems to be - can you minimize your odds of error.

The market is a pendulum that forever swings between unsustainable optimism (which makes stocks too expensive) and unjustified pessimism (which makes them too cheap). The intelligent investor is a realist who sells to optimists and buys from pessimists.

No statement is more true and better applicable to Wall Street than the famous warning of Santayana: "Those who do not remember the past are condemned to repeat it".