Sixtus V (1520-1590) was pope from 1585 to 1590. A keenly intelligent man of driving energy and determination, he left his clear impress on the internal organization of the Church and on the physical character of Rome.

Felice Peretti, who became Sixtus V, was born on Dec. 13, 1520, in the village of Grottammare in the Mark of Ancona. His parents were poor, and as a boy he did the hard physical work of a peasant. At the age of 14 he entered the Conventual Franciscans. In his studies, which he pursued in various cities of northern Italy, he manifested a clear and forceful intelligence. In 1547 he was ordained a priest at Siena and the following year received his doctorate in theology from the University of Fermo. His abilities as a preacher and his deep concern for reform in the Church brought him to the attention of prominent churchmen in Rome, including two...