Every capitalist economy struggles with how to come to terms with greed, says John Paul Rollert, an expert on the intellectual history of capitalism. He describes how our perspective has changed from the Christian view of greed as an unalloyed sin, to the 18th century idea that it could bring positive benefits, to the unabashed "Greed is good" ethos in the movie "Wall Street." Where do we stand now? How can we rehabilitate capitalism?