1875-1941

French Mathematician

Like many another mathematical innovator, Henri Lebesgue was not immediately recognized for his principal achievement, in his case a new approach to integral calculus. As so often happens with groundbreaking ideas, his integration theory offended prevailing sensibilities. In time, however, Lebesgue would see his ideas accepted—not only in Poland and America but even in his homeland.

Born in the town of Beauvais on June 28, 1875, Lebesgue was the son of a typographical worker and an elementary school teacher. In 1894 he entered the Ecole Normale Supérieure, where he became distinguished both for his sharp mind and for his rather cavalier approach to his studies—an early sign of the unorthodox attitude that would characterize his work on integrals. After graduating in 1897, he worked for two years at the school's library before going on to a teaching position...