"Graham's favorite allegory is that of Mr. Market, an obliging fellow who turns up every day at the shareholder'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."