Pietro Mengoli (1626–1686) was a Catholic priest and a mathematician. He studied under Bonaventura Cavalieri (1598–1647) at the University of Bologna and when his teacher died, Mengoli assumed the Chair of Mathematics held by Cavalieri. His *Geometriae speciosae* *elementa* (1659) is a study of the limits of geometrical figures. In this book, Mengoli introduced a concept of the definite integral as the area contained by a curve.

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