Reigned 468-483; date of birth unknown; died 10 March, 483. According to the "Liber Pontificalis" (ed. Duchesne, I, 249) Simplicius was the son of a citizen of Tivoli named Castinus; and after the death of Pope Hilarius in 468 was elected to succeed the latter. The elevation of the new pope was not attended with any difficulties. During his pontificate the Western Empire came to an end. Since the murder of Valentinian III (455) there had been a rapid succession of insignificant emperors in the Western Roman Empire, who were constantly threatened by war and revolution. Following other German tribes the Heruli entered Italy, and their ruler Odoacer put an end to the Western Empire by deposing the last emperor, Romulus Augustulus, and assuming himself the title of King of Italy. Although an Arian, Odoacer treated the Catholic Church with much respect; he also retained the greater part of the former administrative organization, so that the change produced no great differences at Rome. During the Monophysite controversy, that was still carried on in the Eastern Empire, Simplicius vigorously defended the independence of the Church against the Cæsaropapism of the Byzantine rulers and the authority of the Apostolic See in questions of faith. The twenty-eighth canon of the Council of Chalcedon (451) granted the See of Constantinople the same privileges of honour that were enjoyed by the Bishop of Old Rome, although the primacy and the highest rank of honour were due to the latter. The papal legates protested against this elevation of the Byzantine Patriarch, and Pope Leo confirmed only the dogmatic decrees of the council. However, the Patriarch of Constantinople sought to bring the canon into force, and the Emperor Leo II desired to obtain its confirmation by Simplicius. The latter, however, rejected the request of the emperor and opposed the carrying out of the canon, that moreover limited the rights of the old Oriental patriarchates.

The rebellion of Basiliscus, who in 476 drove the Emperor Zeno into exile and seized the Byzantine throne, intensified the Monophysite dispute. Basiliscus looked for support to the Monophysites, and he granted permission to the deposed Monophysite patriarchs, Timotheus Ailurus of Alexandria and Peter Fullo of Antioch, to return to their sees. At the same time he issued a religious edict ( Enkyklikon) addressed to Ailurus, which commanded that only the first three ecumenical synods were to be accepted, and rejected the Synod of Chalcedon and the Letter of Pope Leo. All bishops were to sign the edict. The Bishop of Constantinople, Acacius (from 471), wavered and was about to proclaim this edict. But the firm stand taken by the populace, influenced by the monks who were rigidly Catholic in their opinions, moved the bishop to oppose the emperor and to defend the threatened faith. The abbots and priests of Constantinople united with Pope Simplicius, who made every effort to maintain the Catholic dogma and the definitions of the Council of Chalcedon. The pope exhorted to loyal adherence to the true faith in letters to Acacius, to the priests and abbots, as welI as to the usurper Basiliscus himself. In a letter to Basiliscus of 10 Jan., 476, Simplicius says of the See of Peter at Rome: "This same norm of Apostolic doctrine is firmly maintained by his (Peter's) successors, of him to whom the Lord entrusted the care of the entire flock of sheep, to whom He promised not to leave him until the end of time" (Thiel, "Rom. Pont.", 182). In the same way he took up with the emperor the cause of the Catholic Patriarch of Alexandria, Timotheus Salophakiolus, who had been superseded by Ailurus. When the Emperor Zeno in 477 drove away the usurper and again gained the supremacy, he sent the pope a completely Catholic confession of faith, whereupon Simplicius (9 Oct., 477) congratulated him on his restoration to power and exhorted him to ascribe the victory to God, who wished in this way to restore liberty to the Church.

Zeno recalled the edicts of Basiliscus, banished Peter Fullo from Antioch, and reinstated Timotheus Salophakiolus at Alexandria. He did not disturb Ailurus on account of the latter's great age, and as matter of fact the latter soon died. The Monophysites of Alexandria now put forward Peter Mongus, the former archdeacon of Ailurus, as his successor. Urged by the pope and the Eastern Catholics, Zeno commanded the banishment of Peter Mongus, but the latter was able to hide in Alexandria, and fear of the Monophysites prevented the use of force. In a moment of weakness Salophakiolus himself had permitted the placing of the name of the Monophysite patriarch Dioscurus in the diptychs to be read at the church services. On 13 March, 478, Simplicius wrote to Acacius of Constantinople that Salophakiolus should be urged to wipe out the disgrace that he had brought upon himself. The latter sent legates and letters to Rome to give satisfaction to the pope. At the request of Acacius, who was still active against the Monophysites, the pope condemned by name the heretics Mongus, Fullo, Paul of Epheseus, and John of Apamea, and delegated the Patriarch of Constantinople to be in this his representative. When the Monophysites at Antioch raised a revolt in 497 against the patriarch Stephen II, and killed him, Acacius consecrated Stephen III, and afterwards Kalendion as Stephen's successors. Simplicius made an energetic demand upon the emperor to punish the murderers of the patriarch, and also reproved Acacius for exceeding his competence in performing this consecration; at the same time, though, the pope granted him the necessary dispensation. After the death of Salophakiolus, the Monophysites of Alexandria again elected Peter Mongus patriarch, while the Catholics chose Johannes Talaia. Both Acacius and the emperor, whom he influenced, were opposed to Talaia, and sided with Mongus. Mongus went to Constantinople to advance his cause. Acacius and he agreed upon a formula of union between the Catholics and the Monophysites that was approved by the Emperor Zeno in 482 ( Henotikon). Talaia had sent ambassadors to Pope Simplicius to notify the pope of his election. However, at the same time, the pope received a letter from the emperor in which Talaia was accused of perjury and bribery and a demand was made for the recognition of Mongus. Simplicius, therefore, delayed to recognize Talaia, but protested energetically against the elevation of Mongus to the Patriarchate of Alexandria. Acacius, however, maintained his alliance with Mongus and sought to prevail upon the Eastern bishops to enter into Church communion with him. For a long time Acacius sent no information of any kind to the pope, so that the latter in a letter blamed him severely for this. When finally Talaia came to Rome in 483 Simplicius was already dead.

Simplicius exercised a zealous pastoral care in western Europe also, notwithstanding the trying circumstances of the Church during the disorders of the Migrations. He issued decisions in ecclesiastical questions, appointed Bishop Zeno of Seville papal vicar in Spain, so that the prerogatives of the papal see could be exercised in the country itself for the benefit of the ecclesiastical administration. When Bishop John of Ravenna in 482 claimed Mutina as a suffragan diocese of his metropolitan see, and without more ado consecrated Bishop George for this diocese, Simplicius vigorously opposed him and defended the rights of the papal see. Simplicius established four new churches in Rome itself. A large hall built in the form of a rotunda on the Cælian Hill was turned into a church and dedicated to St. Stephen; the main part of this building still exists as the Church of San Stefano Rotondo. A fine hall near the Church of Santa Maria Maggiore was given to the Roman Church and turned by Simplicius into a church dedicated to St. Andrew by the addition of an apse adorned with mosaics; it is no longer in existence (cf. de Rossi, "Bull. di archeol. crist.", 1871, 1-64). The pope built a church dedicated to the first martyr, St. Stephen, behind the memorial church of San Lorenzo in Agro Verano; this church is no longer standing. He had a fourth church built in the city in honour of St. Balbina, "juxta palatium Licinianum", where her grave was; this church still remains. In order to make sure of the regular holding of church services, of the administration of baptism, and of the discipline of penance in the great churches of the catacombs outside the city walls, namely the church of St. Peter (in the Vatican), of St. Paul on the Via Ostiensis, and of St. Lawrence on the Via Tiburtina, Simplicius ordained that the clergy of three designated sections of the city should, in an established order, have charge of the religious functions at these churches of the catacombs. Simplicius was buried in St. Peter's on the Vatican. The "Liber Pontificalis" gives 2 March as the day of burial (VI non.); probably 10 March (VI id.) should be read. After his death King Odoacer desired to influence the filling of the papal see. The prefect of the city, Basilius, asserted that before death Pope Simplicius had begged to issue the order that no one should be consecrated Roman bishop without his consent (cf. concerning the regulation Thiel, "Epist. Rom. Pont.", 686-88). The Roman clergy opposed this edict that limited their right of election. They maintained the force of the edict, issued by the Emperor Honorius at the instance of Pope Boniface I, that only that person should be regarded as the rightful Bishop of Rome who was elected according to canonical form with Divine approval and universal consent. Simplicius was venerated as a saint; his feast is on 2 or 3 March.

Liber pontificalis, ed. DUCHESNE, I, 249-251; JAFFÉ, Regesta Pont. Rom., 2nd ed., I, 77-80; THIEL, Epist. Rom. Pontif., I (Brunswick, 1868), 174 sq.; LIBERATUS, Breviar. Causæ Nestor., xvi sq.; EVAGRIUS, Hist. eccl., III, 4 sq.; HERGENRÖTHER, Photius, I, 111-22; GRISAR, Geschichte Roms und der Päpste, I, 153 sq., 324 sq.; LANGEN, Geschichte der römischen Kirche, II (Bonn, 1885), 126 sqq.; WURM, Die Papstwahl (Cologne, 1902).

J.P. KIRSCH