Pierre-Simon Laplace

A letter to d’Alembert on mathematical principles got Laplace a professorship at the École Militaire. He taught Fourier (who however thought Lagrange and Monge better teachers), and encouraged Cauchy. Lagrange was a professional rival, but both gained from the mutual flow of ideas. Laplace and Berthollet founded the influential Société d’Arcueil, whose members included Arago, Poisson, Biot, Gay-Lussac, Malus and Humboldt. With Lavoisier, he showed that respiration was a form of combustion. Biot helped prepare his work for publication, but said that Laplace often forgot his original reasoning, substituting the line “it is easy to see.”