"By age 40, [Michael Faraday] had invented the electric motor, the transformer, the generator; machines that would change everything about the home, the farm, the factory. Now, at 60 . . . plagued by memory loss and melancholy, he fearlessly probed deeper into the mysterious invisible forces. . . . Having discovered the unity of electricity, magnetism and light, Faraday needed to know how this trinity of natural forces work together."