A theory of stock prices which states that the price that an investor pays for a share is not based on the fundamental value of the underlying business, but instead on what other investors would pay for it. It was proposed by British economist John Maynard Keynes in his very popular 1936 book, The General Theory of Employment, Interest, and Money. Keynes said that this behaviour was analogous to how participants would behave in a contest to choose the most beautiful faces from a hundred photographs. Since the winners would be chosen based on the faces that are the most popular, contestants would try to guess the tastes of each other.