[1] Lorenzo Casoni was born in Sarzana[2] on September 10, 1645, the son of Niccolò, count of Villanova, and Giulia Petriccioli.

The family was of noble and religious origins:[3] his cousin was Monsignor Agostino Favoriti, secretary of Pope Innocent XI, to which post he later succeeded.

Pope Innocent XI made him "secret chamberlain of honor" and canon of Santa Maria Maggiore.

On March 3, 1690, he was elected titular archbishop of Caesarea, with dispensation for not receiving the diaconate and presbyterate.

On 12 Mar 1690, he was consecrated bishop by Francesco Nerli (iuniore), Cardinal-Priest of San Matteo in Merulana.