SISTO III, POPE, saint. — He was pope from 432 to 440. There is no evidence that he was venerated in antiquity; he was included by Ado in his Martyrologium, from which he passed into the Roman Martyrology, where he is commemorated on 28 March.
A Roman, the son of the presbyter Sisto, he seems, when he too was a priest, to have sympathized with the Pelagians; but after the condemnation of the heresy by Pope Zosimus (418), he definitively abandoned them and also wrote several vigorous letters against them, so much so that St. Augustine had to urge him to exercise greater prudence and charity. He succeeded Celestine (432), when the Nestorian heresy had already been condemned (Ephesus, 431; as early as 430 he himself had written directly to Nestorius, exhorting him to abandon his error), but he found the Churches of the East divided over the well-known dispute between St. Cyril and John of Antioch. He had, however, the consolation of learning of the peace that had been achieved in 433, and wrote to congratulate the two protagonists. Recalling his former sympathy for the Pelagians, Julian of Eclanum tried to maneuver for his readmission to ecclesiastical communion, but Sisto, advised by Leone, the future pope, was not deceived.
A faithful continuator of the primatial activity of his predecessors, he wrote a letter to Proclus of Constantinople warning him not to interfere in the affairs of Illyricum, while confirming Anastasius of Thessalonica as his vicar for those regions, with the right to confirm the appointments of bishops, adjudicate disputes, and convene and preside over synods. No less important was Sisto’s building activity. In commemoration of the dogmatic definition of Ephesus, which affirmed the divine motherhood of Mary, he rebuilt and enlarged the Liberian Basilica, adorning it with the splendid mosaics still in existence; he arranged the Lateran Baptistery as it can still be seen today; he adorned the confessiones of the basilicas of St. Peter and St. Paul and built a monastery « in catacumbas ».
He died in Aug. 440 and was buried outside the walls near the tomb of St. Lawrence. One of the « apocrypha of Symmachus » (v. SIMMACO), Cesta de Xisti purgatione, concerns Sisto. In 433 the former consul Bassus accused the Pontiff of unchastity. Valentinian III then convened a synod at S. Croce, at which Sisto succeeded in proving his innocence; Bassus was excommunicated. When the latter subsequently died, three months later, the Pope himself wished to preside over the funeral and buried him in St. Peter’s.
Generous and unconstrained in his spending, S. left the papal finances completely exhausted at his death; but he showed particular liberality toward his relatives, who hastened to fill the court, bringing with them numerous fellow countrymen; ecclesiastical and civil offices and benefices were distributed among them with a lavish hand. Bartolomeo, the Pope’s brother, had a son named Leonardo, the “little prefect” of Rome, who soon disappeared; the other brother, Raffaello, had a much larger offspring: Giuliano, who later became Julius II; Giovanni, who became lord of Sinigallia and then prefect of Rome; Luchinetta, first married to a Gara and then to a Franciotti; and Bartolomeo, a Friar Minor, later bishop of Massa and invested with high offices. The Pope also had two sisters: Bianca, married to a Riario (v.), and Luchina, married to a Basso, whose son was Cardinal Girolamo Antonio. During the short time he lived, it was Cardinal Pietro Riario (d. 5 January 1474) who “held both keys” to the Pope’s heart, while Cardinal Giuliano della Rovere, because of his frequent absences, did not exercise predominant influence. The man who instead wielded power, to such an extent that he could be called Ecclesiae imperator, was Girolamo, brother of Cardinal Pietro, who in 1473 had obtained for him the lordship of Imola and the hand of Caterina Sforza.
S. IV’s first objective was the war against the Turks, who were becoming increasingly threatening; at first he considered summoning a council for this purpose; then he sent five cardinal legates to the princes of the West (23 December 1471); finally, together with Naples and Venice, he equipped a fleet that operated in the East under Cardinal Oliviero Carafa and later under Archbishop Lorenzo Zane (1472–73).
Paul II’s policy had been to keep Italy at peace by overcoming the ambitions and jealousies of the princes, while also preserving Rome from its ever-renewed internal discord. At first, faced with the union of Milan, Venice, and Florence, S. IV allied himself with Naples and Siena (1476), which led to the Pazzi conspiracy against Lorenzo de’ Medici, supported by Girolamo Riario (26 April 1478), the excommunication of Lorenzo and the interdict against Florence, and the war waged by Naples and the Pope; when peace was made between Naples and Florence (March 1480), the Pope too joined II. Meanwhile S. IV had formed an alliance with Venice; yet he again had to take measures against the Turkish danger and assist the Knights of St. John in their victorious resistance at Rhodes, as well as intervene alongside the king of Naples when, in July 1480, the Turks seized Otranto, from which they were not expelled until 10 September 1481. Peace in Italy was again disturbed when war broke out between Venice and Ferrara in May 1482; Naples soon also moved against Venice; the Colonna joined Naples and were opposed by the Orsini; the Neapolitan army marched against Rome but on 21 August was defeated at Campomorto by Roberto Malatesta, the papal commander, and peace was made on that front on 24 December 1482. Relations with Venice, which aimed to seize Ferrara, grew more bitter instead. S. IV pronounced the interdict against Venice on 24 May 1483 and allied himself with Ferrara and Mantua; the Peace of Bagnolo (7 August 1484) between Milan and Venice brought these struggles to an end. But Rome itself could not remain at peace, because of the turbulence of its citizens; bloody conflicts indeed took place between the Santacroce and the Della Valle, complicated by those between the Orsini and the Colonna; the latter were opposed by Count Giacomo Riario; the execution of the protonotary Lorenzo Colonna, head of his house (30 June 1484) and a fierce rival of Riario, did not suffice to extinguish the discord.
S. IV celebrated the Jubilee in 1475; but he was unable to promote an effective reform in the Church, and during his pontificate abuses long deplored increasingly took root in ecclesiastical discipline. S. IV did not fail to take measures for the development of agriculture around Rome and for the city’s grain supply; but, in order to raise money, he increased the number of venal offices and filled the Curia with new officials. He was very munificent toward the Vatican Basilica, built the Sistine, or New, Chapel, inaugurated in 1483, rebuilt the churches of the Holy Apostles and of his Order, S. Maria del Popolo for the Augustinians, and S. Maria della Pace with its cloister for the Canons Regular; and he provided for the arrangement of the Vatican Library. For the convenience and embellishment of the city he rebuilt the Ponte Sisto and undertook to make many streets wider, cleaner, and paved, removing eyesores and obstacles. In this he stimulated the emulation of curials and cardinals in building palaces; sumptuous funerary monuments crowded into the churches; painters, sculptors, and architects among the most illustrious, who had come from every quarter, were able to lend new splendor to the city, which was being renewed according to the canons of Renaissance art, while scholarship too found ever greater favor. S. IV died on 12 August