“It has been called the hardest test, of any kind, in the world. Its rigors have been likened to those required to earn a degree in law or medicine. It is without question a unique intellectual, psychological and physical ordeal, demanding unnumbered thousands of hours of immersive study.” The NYT’s Judy Rosen provides a study guide to The Knowledge: the test to become a London Cabby. Between Uber and GPS, the world’s hardest test might soon be relegated to history class.