An entertaining biography of a remarkable mathematician: Richard Courant, one of the students of David Hilbert. He was one of the leading forces behind the completion of Klein's dream: a mathematical institute in Göttingen, but was forced to leave all behind because of fascism. Anyway he started again in the USA and build another mathematical institute at New York University. In this book Constance Reid describes the mathematical environment in Göttingen and New York accomplishing the difficult task to makes us feel Mathematics as a living subject.