In the first decade of the 20th century, Henri Lebesgue developed a new approach to integral calculus in order to overcome the restrictions of previous theories. At that time, integration was used to calculate the area under a curve, but if the curve was discontinuous the theory was difficult to apply and left some questions unanswered. Lebesgue's theory of integration circumvented the problems caused by these discontinuities and was compatible with other basic mathematical operations.

Henri Léon Lebesgue was born in Beauvais, France, on June 28, 1875. His father was a typographical worker, and his mother was an elementary school teacher. He entered the École Normale Supérieure in 1894 and quickly demonstrated mathematical talent along with an irreverent attitude that gave him the tendency to ignore subjects that did not interest him. For instance, he passed his chemistry course only by mumbling his answers to the...