Poisson was born on June 21, 1781 in Pithiviers, Loiret, France, the son of a civil servant and retired soldier. Poisson studied to enter the medical profession and received training as a surgeon, but had neither the manual dexterity nor the interest to seriously pursue a medical career. In 1796 he entered the Ecole Centrale in Fontainebleau to study mathematics. Two years later, he made the move to Paris where he enrolled at the Ecole Polytechnique after scoring first place on the entrance examination. In Paris, Poisson studied under Pierre Laplace and Joseph Louis Lagrange impressing both men with his ability. A paper on the theory of equations submitted in 1799 enabled Poisson to not only graduate from the Ecole Polytechnique but to be hired as a teacher there. By 1806, Poisson had attained the rank of Professor by replacing the position vacated by Jean-Baptiste-Joseph Fourier.

Early in his career, Poisson made important...