There are certain names in the history of mathematics to which there attaches a special human interest apart from the mere recital of a list of discoveries. O ne of these is d'Alembert 1.
On the night of November 16, 1717, a gendarme, while making his rounds in Paris, found near the church of Saint-Jean le Rond a newly born infant who had been abandoned to the fate of winter, and had him hurriedly christened with the name of his first r esting place, Jean Baptiste le Rond. Foster parents were found and Jean grew up, known but unrecognized by his mother, pitied and somewhat helped by his father, and soon showed remarkable intellectual powers that spoke for intellectual parentage. His mo ther, Madame de Tencin, sister of a cardinal, has been described by one of d'Alembert's biographers as "small, keen, alert, with a little sharp face like a bird's, brilliantly eloquent, bold, subtle, tireless, a great minister of intrigue, and insatiably ambitious." His father, General Destouches, was a man of large heart, and at his death in 1726 left enough to provide for the boy's education. When Jean was eighteen (1735) he took his bachelor's degree and soon, for reasons unknown, adopted the name of d'Alembert. He prepared for the bar, then took up medicine, and finally devoted his life to mathematics. Friend of Voltaire, collaborator on the Encyclopedie, admirer of Madame du Deffand, and lover of her companion Mademoiselle Julie de Lespina sse, he knew those in France who were best worth knowing and experienced all the joys and sorrows that Paris affords. One of his biographers says:
In himself d'Alembert was always rather a great intelligence than a great character. To the magnificence of the one he owed all that has made him immortal, and to the weakness of the other the sorrows and the failures of his life. For it is by charac ter and not by intellect the world is won 2.
D'Alembert wrote upon mathematics in general 3, the calculus and its applications 4, the theory of differential equations 5, and dynamics 6.
(Smith, pp. 479-480.)