Entering the Dominican order in 1667, Orsini taught philosophy at Brescia, Venetian Republic, before Pope Clement X made him cardinal in 1672. He was successively archbishop of Manfredonia (1675), of Cesena (1680), and of Benevento (1686). He had taken part in five conclaves for the election of popes before the conclave that chose him on May 29. His attack on the extravagance of the cardinals and on the worldliness of ecclesiastics, most forcefully asserted at a provincial council at Rome (1725), had little effect. His own mode of living was noted for its simplicity, as he retained his monastic lifestyle. He even banned the popular lottery in Rome. Unfortunately, he left state affairs almost entirely to the unpopular cardinal Niccolò Coscia, whose abuse of his office to amass riches marred Benedict's reign. Papal relations with the Bourbon monarchies of France and Spain, made difficult by the belief in absolutism that prevailed among European kings in the 18th century, were allowed to deteriorate. He continued the opposition of the papacy to Jansenism, a Roman Catholic movement of unorthodox tendencies that had begun in 17th-century France, although he allowed the Dominicans to preach the Augustinian doctrine of grace, which bordered on the Jansenist teaching. A scholar, Benedict wrote many theological works.