The History of the Popes (Vol. XIX) : From the Close of the Middle Ages examines the pontificate of Pope Gregory XIII (1572–1585). The book highlights various internal reforms within the Catholic Church, the role of the Society of Jesus (Jesuits), and the rise of religious orders during the Counter-Reformation era. Its primary focus is on the struggles and political maneuvers of the papacy in response to the Protestant Reformation in the late 16th century. The author provides an in-depth account of the establishment of seminaries and various colleges, as well as the Church's efforts to enforce discipline. Furthermore, the work reviews the significant roles played by key figures such as Charles Borromeo and the reform of the Carmelite order under the guidance of Teresa of Avila. This comprehensive work spans a total of 40 volumes chronicling the history of 56 popes.