Economist JOHN MAYNARD KEYNES

He hardly seemed cut out to be a workingman's revolutionary. A Cambridge University don with a flair for making money, a graduate of England's exclusive Eton prep school, a collector of modern art, the darling of Virginia Woolf and her intellectually avant-garde Bloomsbury Group, the chairman of a life-insurance company, later a director of the Bank of England, married to a ballerina, John Maynard Keynes--tall, charming and self-confident--nonetheless transformed the dismal science into a revolutionary engine of social progress.

Before Keynes, economists were gloomy naysayers. "Nothing can be done," "Don't interfere," "It will never work," they intoned with Eeyore-like pessimism. But...