Vito Volterra had a major impact on the development of calculus, and he originated the concept of a theory of functions. Perhaps his most famous work was on integral equations.

Volterra was born to a poor cloth salesman on May 3, 1860 in Rome, Italy. The Volterras became virtually destitute when Mr. Volterra died when Vito was about two, so the boy and his mother moved in with her brother. Volterra grew up mainly in Florence, attending the Istituto Tecnico Galileo Galilei and the Scuola Tecnica Dante Aligheri. An extremely precocious child, Volterra became interested in the geometry of Adrien-Marie Legendre at age 11, and was soon devising original problems that he would then try to solve.

With his obvious interest in science and mathematics, Volterra rebelled against his family's insistence that he become a bank clerk or similar professional. However, an uncle intervened and persuaded Volterra's relatives to let the...