The French mathematician Augustin Louis Cauchy (1789-1857) provided the foundation for the modern period of rigor in analysis. He launched the theory of functions of a complex variable and was its authoritative pioneer developer.

Augustin Louis Cauchy was born in Paris on Aug. 21, 1789, 38 days after the fall of the Bastille. His father, Louis François, was a parliamentary lawyer, lieutenant of police, and ardent royalist. Sensing the political wind, he moved the family to his country cottage at Arcueil, where they lived for nearly 11 years. Here young Cauchy received a strict religious education from his mother and an elementary classical education from his father, who wrote his own textbooks in verse.

By 1800 the political situation had stabilized and the family moved back to Paris. At the age of 16 Cauchy entered the École Polytechnique, at that time the best school in the world for a budding mathematician...