Lagrange

Abstract

Joseph Louis Lagrange lived from 1736 to 1813. Born in Turino, he had both French and Italian ancestors. His family was well off but Lagrange’s father lost the family fortune in risky financial transactions. This is said to have prompted Lagrange to remark, “Had I inherited a fortune I would probably not have fallen prey to mathematics.” (cf. E. T. Bell, Men of Mathematics). As a youth Lagrange was more interested in classical languages than in mathematics, but his interest in mathematics was stirred by a paper by Halley, the friend of Newton. In a short time he acquired a deep knowledge of analysis; only 19 years old, he became Professor at the Royal School of Artillery in Turino. Lagrange stayed there for about 10 years. His reputation as a mathematician grew quickly, mainly by basic contributions to analysis, specifically the calculus of variations, the theory of differential equations, and mechanics. This combination of mathematics and mechanics or, more generally, theoretical physics, is typical of the eighteenth century. Mathematics was not viewed as an end in itself but mostly as a tool for understanding nature. In 1766, d’Alembert was instrumental in bringing Lagrange to succeed Euler at the Berlin Academy of Science. Financial conditions in Berlin were very good; moreover, he could devote himself exclusively to his mathematical work. Lagrange stayed there until 1787 when he moved to the Academie Française in Paris. At that time, soon after Euler’s death, he was recognized as the most important living mathematician. Though Lagrange had had close ties to the French royal family he was not persecuted during the French Revolution. Altogether, the sciences gained importance during the era of the French Revolution and Napoleon. Lagrange’s authority transcended the sphere of science. He was a Senator of the Empire and in fact received a state burial in the Pantheon.