Benjamin Graham - Mr. Market

Graham's favorite allegory is that of Mr. Market, an obliging fellow who turns up every day at the share holder's door offering to buy or sell his shares at a different price. Often, the price quoted by Mr. Market seems plausible, but sometimes it is ridiculous. The investor is free to either agree with his quoted price and trade with him, or ignore him completely. Mr. Market doesn't mind this, and will be back the following day to quote another price.

The point of this anecdote is that the investor should not regard the whims of Mr. Market as a determining factor in the value of the shares the investor owns. He should profit from market folly rather than participate in it. The investor is advised to concentrate on the real life performance of his companies and receiving dividends, rather than be too concerned with Mr. Market's often irrational behaviour.