Keynes and Paul Krugman were walking their dogs in the park, and as one of their dogs leaves a steaming pile of shit on the ground Keynes turns to Krugman and says "I will give you $5,000 to eat that dog shit."<br>Krugman does it and takes the money.<br>The next day they are in the same park, except this time Krugman says "John I will give you an opportunity to win your money back. $5,000 to eat that pile of shit."<br>Keynes does it and Krugman gives him the money, the very same bills that were originally Keynes' to begin with.<br>Then Krugman realizes something and says "John we are such idiots. Both of us ate shit and neither of us has more money than before." Keynes responds simply, "Yes, but we grew the economy by $10,000."