1598-1647

Italian Mathematician

Praised by thinkers ranging from his friend Galileo (1564-1642) to twentieth-century writer Isaac Asimov, Bonaventura Cavalieri is best known for his work on the concept of indivisibles. This laid the foundation for the development of the infinitesimal, and with it calculus as conceived by Sir Isaac Newton (1642-1727).

Cavalieri's true first name is not known: Bonaventura was a religious name adopted when he joined a monastery at age 17. As for the circumstances of his birth, it is known only that he was born in Milan in 1598. In his mid-teens, Cavalieri joined the Jesuatis, an order under the Augustinian rule not to be confused with the Jesuits, and in 1615 took minor orders at a Milan monastery.

The following year found him at another monastery in Pisa, where he came under the influence of Benedetto Castelli, a former student of Galileo. Castelli inspired in his...