The visitor who names a different price every morning

Benjamin Graham imagined an obliging business partner, later nicknamed Mr Market, arriving daily with a price at which he would buy your share or sell his. His mood swings. The important feature is not the visitor's psychology but your freedom: a quotation is an offer, not an instruction.

The allegory was written for securities analysis, and estimating underlying value is uncertain work rather than a hidden number waiting to be found. Markets can also contain information an individual lacks. Even so, Graham's visitor survives because he separates availability from obligation. A doorbell may ring each morning; nothing requires the person inside to answer.