In uncertain financial times, it seems every economist has their own opinion on how to revive the economy. But the idea that we could study the marketplace and deduce how to control and improve it was once radical. Decades before the Great Recession, students studied economics in order to become masters of their own fate. A new book examines the development of economic theory, from the Age of Industrial Revolution to World War II. Sylvia Nasar, author of the book, “Grand Pursuit: The Story of Economic Genius,” talks about what modern economists can learn from the early masters.