French mathematician, c. 1601-65
Fishburn and Hughes: "A distinguished French mathematician, in his day second only to René Descartes, some of whose ideas he disputed. Fermat was considered by some the discoverer of differential calculus and is credited as the founder of the modern theory of numbers.
The story is told that, while reading an edition of the Arithmetica of Diophantus, Fermat discovered an important theory of higher mathematics which he noted on the margin of his copy but did not bother to set out fully. It has never been reconstructed. Fermat was reluctant to give demonstrations of his results, and it was often left to others to provide the proofs of his theories." (71)