Pierre Fermat (20.08.1601-12.01.1665) was a French mathematician and physicist. He was born in Beaumont-de-Lomagne. He received a legal education. From 1631 he was a councillor of the parliament in Toulouse.
His physical research was for the most part in optics, where he established (about 1662) the fundamental principle of geometrical optics (Fermat's principle), according to which light travels between two points along the path that takes the least time to traverse. The analogy between Fermat's principle and the variational principles of mechanics played a considerable role in the development of modern dynamics and of the theory of optical instruments.