 In 1827 appeared his "History of the Progress and Suppression of the Reformation in Italy," a work that had formed the subject of his earlier studies, but for many years had been laid aside.It was a most complex and laborious task, as he was obliged to trace the origin, progress, and decline of the Reformation through twenty-five of the Italian states, among which the great movement was divided.Such was the interest of this work, that it was translated into French, German, and Dutch, and inserted by the ecclesiastical tribunal of Rome in the "Index Expurgatorius".