Lagrange spoke to Laplace about an 11-year child:

“You see that little young man? Well! He will supplant all of us in so far as we are mathematicians.”

That 11-year old child was none other than Augustin Louis Cauchy who was born on August 21, 1789, in Paris, the eldest of six children. By 1800, both Laplace and Lagrange recognized Cauchy’s extraordinary talent for mathematics. In school he won prizes for Greek, Latin, and the humanities. At the age of 21, he was given a commission in Napoleon’s army as a civil engineer. For the next few years, Cauchy attended to his engineering duties while carrying out brilliant mathematical research side by side.

At the age of 26, Cauchy was made Professor of Mathematics at Ecole Polytechnique and was recognized as the leading mathematician in France. Cauchy and his contemporary Gauss were the last men to know the whole of mathematics as known at their time, and both made important contributions to nearly every branch, both pure and applied, as well as to physics and astronomy.

Cauchy introduced a new level of rigour into mathematical analysis. We owe our contemporary notions of limit and continuity to him. He gave the first proof of the Fundamental Theorem of Calculus. Cauchy was the founder of complex function theory and a pioneer in the history of permutation groups and determinants. His total written output of mathematics fills 24 large volumes and is second only to that of Euler. He wrote over 500 research papers after the age of 50. Cauchy died at the age of 67 on May 23, 1857.