Both individual skill (art) and chance are important factors in determining success or failure.

Losing some money is an inevitable part of investing, and there's nothing you can do to prevent it. But to be an intelligent investor, you must take responsibility for ensuring that you never lose most or all of your money.

The intelligent investor is a realist who sells to optimists and buys from pessimists.

In other words, the market is not a weighing machine, on which the value of each issue is recorded by an exact and impersonal mechanism, in accordance with its specific qualities. Rather should we say that the market is a voting machine, whereon countless individuals register choices which are the product partly of reason and partly of emotion.

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.

Buy not on optimism, but on arithmetic.

Nothing important on Wall Street can be counted on to occur exactly in the same way as it happened before.