who, with Lagrange and Laplace, formed a trio associated with the period of the French Revolution. He was well known in the 19th century for his highly successful textbook on the geometry of Euclid. But his real work was concerned with calculus. He was responsible for the classification of elliptic integrals into their standard forms. The so‐called Legendre polynomials, solutions of Legendre’s differential equation, are among the most important of the special functions. In an entirely different area, he, along with Euler, conjectured and partially proved an important result in number theory known as the law of quadratic reciprocity.