SISTO I, POPE, saint. - The sixth successor of the Apostles, his pontificate may approximately be placed between 115 and 125. Floro was the first to include him in his Martyrology, whence he passed into the Roman one, in which he is commemorated on 6 August as a martyr; but this status is not established, being unknown to the ancient ecclesiastical sources.
The author of the Liber Pontificalis calls him a Roman, son of a certain Pastore. The chronology of his pontificate is uncertain, as indeed is that of the popes of the first two centuries. According to Eusebius (Hist. eccl., IV, 5), he succeeded Alessandro and died in 128–29 after about ten years of episcopate; according to the Liberian Catalogue, however, he died in 126. He is credited with a decree establishing that only ministers might touch the sacred vessels, and that the people in liturgical assemblies should sing the Sanctus after its intonation by the celebrating priest. He was buried in the Vatican.