French mathematician and mathematical physicist who was the greatest mathematician of the eighteenth century. His work Mécanique Analytique (Analytical Mechanics) (1788) was a mathematical masterpiece. It contained clear, symmetrical notation and covered almost every area of pure mathematics. It was the first book of mechanics published without the use of a single diagram. Lagrange succeeded Euler as the director of the Berlin Academy.

Lagrange developed the calculus of variations which was later expanded by Weierstraß. Lagrange also established the theory of differential equations, and provided many new solutions and theorems in number theory, including Wilson's theorem. Lagrange's classic Théorie des fonctions analytiques laid some of the foundations of group theory, anticipating Galois. Lagrange also invented the method of solvingdifferential equations known as variation of parameters. Lagrange commented that "I have always observed that the pretensions of all people are in exact inverse ratio to their merits; this is one of the axioms of morals" (Bell 1937, p. 160).

Additional biographies: MacTutor (St. Andrews), Dublin Trinity College, Bonn