(768-772), born Sicily, c.720; died Rome. A Benedictine, his election was opposed by the antipopes Constantine and Philip. During his pontificate the Lateran Council declared that only cardinals might become pope, and deprived laymen of any part in the election. With the aid of the Franks he regained territory from the Lombards. A decree of his, which is in force today, permits only the pope or specially appointed cardinals to offer Mass on the high altar in the Lateran.