**Francesco Bonaventura Cavalieri** was an Italian mathematician and astronomer born in 1598 in the city of Milan. He is known mainly for the *Cavalieri Principle*, which assists in the calculation of solids volumes.

Professor at the University of Bologna, invented the method of indivisibles (1635), ushering in a new era for geometry and paving the way for the introduction of integral calculus. He joined the Jesuit order in Milan (1615) and moved to the monastery of Pisa (1616), where he became interested in mathematics after meeting Galileo through Cardinal Federico Borromeo.

In 1621, he became assistant to Cardinal Federico Borromeo at the monastery of Milan. After teaching theology, he became prior of St. Peter in Lodi (1623). After three years in Lodi, he went to the monastery of Parma and was appointed chair of mathematics in Bologna (1629), when he was already developing the famous theory of indivisibles, which he presented in his work. *Geometry indivisibilis continuorum nova* (1635).

After many centuries, this theory simplified the calculation of areas and volumes of various geometric figures. He was also responsible in Italy for introducing the logarithm of trigonometric functions for use in astronomy calculations, with the book *Directorium Generale Uranometricum*. He also wrote about conical sections, trigonometry, optics, astronomy and astrology.

He kept in touch with many mathematicians of the time, such as Galileo, Mersènne, Renieri, Rocca, Torricelli and Viviani. Your last book was *Trattato della ruota planetaria perpetua *(1646). He died in Bologna in the year 1647.