1717-1783

French Mathematician and Physicist

The name of Jean Le Rond d'Alembert belongs among the most honored of the philosophes, French thinkers whose ideas exemplified the Enlightenment. D'Alembert is most readily associated with Denis Diderot (1713-1784), to whose Encyclopédie he was a significant contributor. As a mathematician and physicist, his contributions include d'Alembert's principle, an extension of Newton's third law of motion.

D'Alembert's early years were not happy ones. His mother, Claudine-Alexandrine Guérin, marquise de Tencin, was a former nun who lived with a number of men—including, for a short time at least, Louis-Camus, chevalier Destouches-Canon, a military officer. From this union, a son was born in Paris on November 17, 1717, but the mother regarded her pregnancy as an unpleasant interruption in her affairs, and abandoned the infant on the steps of the church at Saint-Jean-le-Rond...