December 1957. As snow swirls around a garage-turned workshop in northeast Minneapolis, the young man inside hunches over a collection of wires, resistors, switches, and other electrical bits and pieces. History is being made: The man is Earl Bakken, and the device taking shape in his hands is the world's first wearable transistorized pacemaker. By summer, his invention will be keeping young children alive after open-heart surgery. By 2007, the device and others based on it will have given millions of individuals around the world a new chance to lead healthy lives.