Michael Freedman’s momentous 1981 proof of the four-dimensional Poincaré conjecture was on the verge of being lost. The editors of a new book are trying to save it. One of the most important pieces of ...

Every mathematician has a story that goes something like this. You’re at a party, and someone asks what you do for a living. “I’m a mathematician,” you say. “You must be a genius!” they reply. Or ...