All atomic particles have a particular "spin," analogous to the rotation of the Earth about its axis. Simple as spin may sound, the quantum mechanical reality underlying it is complex and still poorly understood. Yet this mysterious quality and the statistics associated with it have vast practical importance to topics as wide-ranging as the stability of atoms and stars and magnetic resonance imaging. Originally published in 1974, Sin-Itiro Tomonaga's "The Story of Spin" is an accessible treatment of the subject, now available in English translation. Tomonaga relates the story of the pioneers of physics and their difficult journey toward an understanding of the nature of spin and its relationship to statistics. His discussion of spin should interest advanced scientists studying the foundations of modern physics, while his description of the little-known history of the Japanese physics community from the 1920s to the 1940s should be a useful resource for historians and philosophers of science.