Pierre de Fermat (1601–1665) is on every list of great mathematicians. However, he had a day job as a judge in Richelieu’s France and his great theorems were scribbled, with little or no proof, in the margins of a book. About his Last Theorem he tantalisingly noted: ‘I have discovered a truly marvellous demonstration which this margin is too narrow to contain.’ That was certainly true: when Andrew Wiles, a Cambridge man now in Princeton, succeeded in 1994, his proof needed 130 pages and a whole library of higher mathematics besides.

Fermat worked in the Parlement of Toulouse, an institution somewhat resembling our House of Lords in that it was a supreme law court, staffed by nobles – albeit the somewhat inferior ‘noblesse de robe’ – and in having power to delay government legislation. A century after Fermat, Calas, a Protestant,