Born of the senatorial family of the Colonnas, Sixtus was created pontiff on the 29th of May, 119. He was the first to direct that the chalice and the paten should be touched only by the sacred ministers. Caesarotti remarks that if the pagan philosophers held in honor the names of the Eumolpuses, the Orpheuses, and the Numas, because they originated or added to the pomp of the worship of their fantastic deities, into which those pagans introduced superstitions and absurd ceremonies, we ought to contemplate with respect the pontiffs who, like Saint Alexander and Saint Sixtus, successively, and in accordance with the Christian spirit, labored to render more venerable the most august of all our mysteries.
Under the reign of Saint Sixtus there was less persecution. A proconsul still more courageous than Pliny represented to the Emperor Adrian how unjust it was to inflict cruel tortures, without examination and trial, from mere prejudice against a class whose only fault, in the estimation of all reasonable Romans, consisted in the name of Christian. That proconsul was Serenius Granianus. History should display in letters of gold the name of that minister who ventured to expose himself to the hatred of the prince in defence of truth and justice. The emperor was moved, and the apologies which were presented to him by Quadratus and Aristides completely appeased him. Adrian wrote a memorable letter in favor of the Christians, strictly forbade denunciations of them, and ordered that those who offended in that wise should be punished. This showed that if he had not already learned to worship Jesus, he had at least learned to venerate him. Ere long, however, the inconsistent prince suffered persecution to begin again. Sixtus was its victim.
Full of generous and considerate ideas, Sixtus had ordered that no bishop having been summoned to Rome, and subsequently returning to his bishopric, should be received there, except on his presenting to his people apostolic letters called formatae. These recommended the unity of the faith, and a mutual love between the head of Catholicity and the children of Jesus Christ. Besides the letters called formatae (the formatae – formed – were so named on account of the seal or of the especial form used in writing them) there were others termed canonicals, which were delivered to the bishops when they were about to return to their dioceses. Still more explicit than the formatae, they tended to strengthen and render unalterable the unity of the faith, obedience to the Holy See, the charity of the pope, and that of the members of the Church. The word canonicals well explains the sense of those letters. To prevent all system of fraud, those letters were sanctioned by the first Council of Nice, which prescribed their tenor, and in some sort even the cipher in which they should be written; for their language was not intelligible to all. There were letters called pacifics, or communicatives. These letters were given to pilgrims, and testified to their Catholic faith and to their communion with the church in which they lived. Letters commendatory served pilgrims in their travelling expenses.
There were already letters dimissory, by which a cleric could prove that he was absent from his diocese by permission of his bishop. There were also memoriales, or letters commonitory; they contained instructions to the legates for the fulfilment of the commissions with which they were entrusted. And there were synodals, which were issued on various occasions. They were called encyclicals or circulars, and catholicals, when they were addressed to all the churches. They were called decretals when the Roman pontiffs issued them in response to various questions, or to prescribe the performance or the omission of some act. Pastoral letters were those of the bishops to their flocks. Letters confessory were those given to the Christians who, in times of persecution, were imprisoned for the sake of Jesus. They recommended to the bishops those weak-minded men who in their terror of torture had denied the faith; and served afterwards to admit these uncourageous Christians to penitence and rehabilitation. Apostolic letters were those which emanated from the Roman pontiffs, in virtue of the apostolic authority. These were of various kinds. Some were called briefs, by which name the ancients understood the documents which described the ecclesiastical property, or what we should now call inventories. The name of brief has become a generic term, and is applied to all the missive letters of the Roman pontiffs. There were, still further, letters that were called clericals, which were issued by the clergy during the vacancy of sees. Saint Augustine speaks of letters termed trattatory, by which princes invited the bishops to attend councils. The same name was given to those letters by which bishops communicated to other bishops what had taken place with respect to any business or question of importance. Letters not noted by a title or other public sign were termed private.
It has been maintained that Saint Sixtus styled himself bishop of bishops. But this assertion rests only on an apocryphal letter, as Marca and Baluze observe. Tertullian, who flourished at the commencement of the third century, adopts that style and title in speaking of the Roman pontiffs. Saint Sixtus created four bishops, nine priests, and three deacons, and governed the Holy See during nearly nine years.
- from "The Lives and Times of the Popes", by Alexis-François Artaud de Montor