John Nash was, arguably, a genius. He certainly believed he was one. Most of his papers in game theory—the work for which he won the Nobel Prize in economics—were written by the time he was 25 years old. Subsequently, he wrote some fundamental papers in mathematics and theoretical physics. But it all ended by the time he was in his late twenties. Nash began suffering from delusions. At the age of 30 he had to be confined to a mental asylum and, for the next thirty years, he was in and out of mental homes, unable to work, incapable of relating to people, a hostage to the demons in his head, paralysed by fear and paranoia.

Unlike other Nobel laureates in economics, John Nash was not prodigious. Depending on how one counts, he wrote a total of three or four papers in economics and game theory. But these papers grew to be classics. ‘Nash’ became an adjective. When a group of self-seeking individuals interact—for instance, several producers of a commodity, deciding how to set prices and what marketing strategy to follow—what outcome can we expect? Nash described a general method for locating the outcome, which came to be known as the ‘Nash equilibrium’. This and the ‘Nash bargaining solution’ became standard tools of modern economic analysis. In classrooms and seminars people talked about the properties of the Nash equilibrium and used his ideas, but very few knew anything about the reclusive man behind this work.