Pope Felix IV governed the Roman Church for only about four years, from July 526 until September 530, yet his short pontificate touched several of the most important religious and political questions facing Christianity in the early sixth century. He entered office while Italy remained under Ostrogothic rule, dealt with a monarchy whose rulers were Arians governing a largely Nicene Christian population, intervened in disputes over clergy and church property, corresponded with Caesarius of Arles, contributed to the theological setting of the Second Council of Orange, transformed ancient Roman buildings into one of the most remarkable churches of the period, and ended his life by attempting to determine who would succeed him as bishop of Rome.
Much of what survives about Felix comes unusually close to his own lifetime. The early portion of the Liber Pontificalis appears to have taken shape within years of his death, while the state papers collected by Cassiodorus preserve the language of the Ostrogothic government itself. Felix’s own letter to Caesarius survives, as does a decree involving the church at Ravenna. The records of the Council of Orange, his succession decree, inscriptions, and the great mosaic of Saints Cosmas and Damian provide additional evidence that allows his pontificate to be reconstructed from far more than later medieval legend.
Felix is sometimes called Felix III in older books. The difference comes from whether the fourth-century antipope Felix II is included in the numbering. Modern papal lists generally identify the sixth-century pope as Felix IV. The Holy See dates his pontificate from July 12, 526, until September 20 or 22, 530.
A Pope Chosen in the Shadow of Theodoric
Felix came to the papacy under difficult circumstances. His predecessor, Pope John I, had been sent by the Ostrogothic king Theodoric to Constantinople on a diplomatic mission involving the treatment of Arians in the Eastern Roman Empire. Theodoric had once maintained a workable relationship with Italy’s Nicene Christian majority, but tensions with Constantinople had increased sharply during the final years of his reign. He became suspicious that Roman political and ecclesiastical elites might favor the eastern emperor over Gothic rule.
John returned from Constantinople without satisfying Theodoric. The pope was arrested at Ravenna and died there on May 18, 526. His death left the Roman Church without a bishop at a moment when relations between the Gothic monarchy and the Catholic population were especially strained.
The Liber Pontificalis says that Felix was a native of Samnium and the son of a man named Castorius. One early form of the text states with unusual directness that Felix was ordained at the command of Theodoric. Cassiodorus provides important confirmation from the Gothic side. In a message issued by Theodoric’s successor Athalaric, the Roman senators were reminded that they had followed the judgment of the late king in the episcopal election. The document even acknowledges that Theodoric belonged to a different confession while presenting his intervention as an attempt to provide Rome with a suitable bishop.
The surviving evidence suggests that the election had been contested. John I died in May, yet Felix was not consecrated until July 12. Cassiodorus’s language appears to refer to an earlier candidate whose cause had been displaced by royal intervention. We do not know that man’s identity with certainty, although historians have sometimes wondered whether he might have been Dioscorus, the same Roman deacon who would emerge as a rival candidate after Felix’s death four years later.
Felix therefore began his pontificate carrying the political weight of Theodoric’s support. His later actions make clear, however, that he was not merely a passive Gothic appointment. During his four years in office he worked to strengthen ecclesiastical discipline, Roman clerical jurisdiction, papal influence beyond Italy, and the material position of the Roman Church.
From Samnium to the Roman Clergy
Almost nothing certain survives about Felix’s early life beyond his Samnite origin and his father’s name. There is, however, an intriguing possibility that he had already participated in one of the major church negotiations of the previous decade.
Jean-Marie Sansterre and other scholars have suggested that Felix may be identical with a Roman deacon who traveled to Constantinople in 519 and 520 as part of Pope Hormisdas’s delegation during the settlement of the Acacian Schism. The identification cannot be proven, but if correct it would mean that Felix had already gained experience in diplomacy and relations with the imperial church before becoming pope.
What is certain is that by 526 he belonged to the Roman clergy and possessed enough standing to become Theodoric’s preferred candidate for the papacy. The number of priests ordained during his pontificate was unusually large according to the Liber Pontificalis. Historians have debated whether this reflected normal institutional needs or an attempt to reshape a Roman clergy in which Felix had initially faced opposition. Whatever the reason, the Roman Church that emerged from his pontificate was not simply continuing unchanged from the age of John I.
Athalaric, Amalasuntha, and the Roman Church
The political situation changed only weeks after Felix’s consecration. Theodoric died in August 526. The Gothic throne passed to his young grandson Athalaric, while real authority was exercised by the boy’s mother, Amalasuntha.
The new government initially pursued a more conciliatory policy toward the Roman elite and the Catholic Church. Cassiodorus, who composed official documents for the Gothic administration, provides some of the clearest evidence for this relationship.
One particularly significant royal rescript, preserved as Variae 8.24, responded to complaints from the Roman clergy concerning legal jurisdiction. The clergy claimed an established privilege under which disputes involving members of the Roman Church should first be brought before the bishop of Rome rather than immediately entering the secular courts. Athalaric recognized the principle and reinforced the pope’s judicial position over Roman clerics.
The episode reveals how difficult it is to describe sixth-century relations between the papacy and the Ostrogothic state simply as conflict between Catholics and Arians. Theodoric had intervened forcefully in Felix’s election, yet his successors could also recognize ecclesiastical privileges that strengthened the bishop of Rome. Royal and papal authority competed in some areas while supporting one another in others.
Felix learned to operate within that complicated political world. The same pope whose election had depended heavily upon a Gothic king could use a Gothic royal decree to reinforce the institutional authority of the Roman Church.
Caesarius of Arles and the Discipline of the Clergy
Felix’s influence extended well beyond Italy through his relationship with Caesarius of Arles, one of the most important bishops in early sixth-century Gaul.
A disciplinary problem had developed concerning men moving directly from secular life into high ecclesiastical office. The Council of Arles in 524 had attempted to impose a period of probation before such ordinations. When enforcement of this rule produced further controversy, including proceedings at the Council of Carpentras in 527, Caesarius sought support from Rome.
Felix responded on February 5, 528. His surviving letter to Caesarius is one of the most valuable documents written directly under his name. Felix approved the principle that a man should not be hurried from secular life into priestly office without testing his character first. He referred to reports of individuals who, after ordination, had returned to secular patterns of behavior and argued that negligence by those responsible for selecting clergy could itself become dangerous.
The letter is revealing because Felix’s language is practical rather than abstract. The issue was not simply whether a technical canonical regulation had been observed. A priest’s conduct affected the credibility of the church he served. Candidates for clerical office therefore needed to demonstrate the stability of their lives before receiving authority over others.
This exchange also demonstrates the continuing importance of Rome to bishops in Gaul. Caesarius was an influential metropolitan in his own right, yet he sought papal support when attempting to enforce reforms that had encountered resistance.
Grace, Free Will, and the Second Council of Orange
The relationship between Felix and Caesarius became even more important during one of the major theological controversies of the early medieval West.
For generations, Christian thinkers had debated the relationship between divine grace and human free will. Augustine of Hippo had emphasized the necessity and priority of God’s grace in salvation. Other theologians, particularly in southern Gaul, feared that certain interpretations of Augustine left too little room for meaningful human response. Modern scholars often group some of these positions under the term Semipelagianism, although the people involved did not ordinarily use that label for themselves.
Caesarius sought assistance from Rome as the controversy continued. The surviving acts of the Second Council of Orange, held on July 3, 529, state that the bishops were acting with the advice and authority of the Apostolic See and that they had received a group of theological capitula, or propositions, from Rome concerning grace and free will. The council incorporated this material into its teaching.
The resulting canons rejected the idea that human beings could make the first saving movement toward God independently of divine grace. Even the beginning of faith, the council insisted, depended upon grace. At the same time, Orange did not teach that human beings were predestined to evil, and its conclusions represented an attempt to defend Augustinian teachings on grace without embracing every extreme interpretation that might be drawn from them.
Felix’s exact role in composing or transmitting the Roman capitula has long been debated. Older scholarship sometimes described the propositions straightforwardly as material sent by Felix, while critical editions have shown that parts of the tradition were older and that the precise stages by which the text reached Caesarius cannot always be reconstructed with certainty. The council itself, however, explicitly identifies material received from the Apostolic See, and Felix’s relationship with Caesarius places his pontificate directly within the theological history that produced Orange.
Felix did not live long enough to complete the final stage of Roman approval. After his death, Caesarius sent the council’s acts to Rome, and Pope Boniface II formally confirmed the teaching in a letter dated January 25, 531. It is therefore more accurate to say that Felix helped shape the Roman involvement leading to Orange, while Boniface provided the later formal confirmation.
The distinction matters because Felix’s importance does not depend upon attributing the entire Council of Orange to him. His pontificate served as an important bridge between Caesarius’s reforming work in Gaul and the theological authority of Rome.
Ravenna and the Government of a Church
Another surviving Felix document opens a window into the everyday problems of governing a major sixth-century church.
A dispute had developed between Bishop Ecclesius of Ravenna and members of his clergy. Felix intervened through a Constitutum de Ecclesia Ravennatensi, a decree preserved centuries later by Agnellus of Ravenna in his Liber Pontificalis Ecclesiae Ravennatis.
The text deals with matters that rarely appear in short biographies of popes but were essential to the operation of the early medieval church. Felix addressed clerical appointments, discipline, income, church property, monasteries, financial distribution, and attempts by clergy to obtain positions through powerful secular patrons. He ordered that candidates for clerical office be judged according to canonical standards rather than influence and prohibited clerical conspiracies and unauthorized factions.
Money receives substantial attention. A portion of the revenues of the church of Ravenna was reserved for distributions among the clergy, while other revenues were assigned to the bishop for expenses connected with administration, hospitality, and the obligations of his office. Records were to make distributions identifiable rather than leaving church income completely opaque.
The decree gives a different picture of papal authority from the theological controversy at Orange. Felix was not only responding to doctrinal questions. He was being asked to resolve disputes involving salaries, offices, discipline, property, and the internal peace of another important Italian church.
Building Christianity into the Roman Forum
Felix’s most visible legacy survives not on parchment but in the center of Rome.
The Liber Pontificalis credits him with constructing the Basilica of Saints Cosmas and Damian on the Via Sacra. Rather than erecting an entirely new monumental complex outside the heart of ancient Rome, the church incorporated existing buildings associated with the Roman Forum and the imperial monumental landscape. In doing so, Felix placed Christian worship directly within one of the most symbolically charged spaces of the old city.
The choice of Saints Cosmas and Damian was also significant. According to Christian tradition, the two were physician martyrs, brothers remembered for healing without demanding payment. Their cult had strong eastern associations, and establishing a major sanctuary dedicated to them in Rome connected the city to devotional traditions circulating across the Mediterranean Christian world.
The basilica’s sixth-century apse mosaic remains one of the most striking visual survivals from Felix’s age.
Christ appears above a dramatic field of clouds, flanked by apostles and saints. Peter and Paul present Cosmas and Damian, while Saint Theodore also appears. At the edge stands Felix himself holding a model of the church he had founded. The donor image makes a clear statement. Felix is shown not merely as an administrator but as the bishop responsible for offering a sacred building to God.
The figure visible today has undergone later restoration, particularly around Felix’s face, so it cannot simply be treated as an untouched sixth-century portrait. Nevertheless, the composition and dedication preserve important evidence for the way papal patronage was represented in Felix’s Rome.
The basilica also illustrates a broader transformation taking place across Rome. Christianity had long been established in the city, but Christian institutions were increasingly absorbing, adapting, and redefining spaces connected to Rome’s imperial past. Felix’s church made that transformation physically visible along the Via Sacra.
The Liber Pontificalis also associates Felix with the restoration of the Basilica of Saint Saturninus after fire damage, while inscriptions have been connected with work at Santo Stefano Rotondo. His architectural patronage therefore appears to have extended beyond a single famous foundation.
Felix in Mosaic and Stone
Felix’s memory was not confined to narrative texts. His inscriptions provide another kind of evidence.
The dedication associated with Saints Cosmas and Damian identifies Felix in connection with the offering of the church. Even more personal is the funerary inscription once associated with his burial at Saint Peter’s. Although the original setting has not survived intact, the text was copied and preserved.
The epitaph praised Felix’s humility, simplicity, generosity to the poor, and assistance to the suffering. It also celebrated the growth of the resources of the Apostolic See during his leadership. Such inscriptions naturally belong to the language of commemoration rather than neutral biography, but they show which qualities Felix’s supporters wanted future generations to associate with his pontificate.
Taken together with the mosaic, the epitaph also demonstrates the expanding visual language of papal office. Felix could be remembered as a pastor of the poor, a custodian of ecclesiastical resources, a builder, and a bishop visibly inserted into the sacred art of Rome.
The Attempt to Choose His Own Successor
Felix’s most controversial decision came at the end of his life.
By September 530 he was gravely ill. Fearing what might happen after his death, Felix attempted to settle the papal succession in advance. His decree, the Praeceptum papae Felicis, survives among a remarkable collection of documents connected with the crisis.
In the presence of priests, deacons, senators, and other leading figures, Felix placed his pallium upon Archdeacon Boniface and publicly designated him as his intended successor. The gesture resembled an investiture rather than a simple private recommendation. Felix specified that if he recovered, the pallium was to be returned, making clear that Boniface was not yet being installed as pope while Felix remained alive.
Felix then publicized the decision. His decree was addressed broadly to bishops, priests, deacons, the clergy, the Senate, and the Roman people, and notice was given to the government at Ravenna.
There was some precedent for a reigning pope indicating a preferred successor. A Roman synod held in 499 had allowed a pope, under certain circumstances, to make such a designation. Felix, however, went much further in the symbolic force of his action. By placing the pallium on Boniface and publicly presenting him as the man who should follow him, Felix appeared to many Romans to be treating the papacy almost as an office whose succession could be transferred by the sitting bishop.
His motive may have been peace. Papal elections in late antiquity could become bitter contests involving competing groups of clergy, aristocrats, and political patrons. Felix himself had come to office after an election shaped by royal intervention. He had good reason to fear what an uncontrolled contest might produce.
Yet the method he chose helped produce the very division he was trying to prevent.
Boniface, Dioscorus, and the Schism of 530
Felix died in Rome on either September 20 or September 22, 530. His designation of Boniface did not settle the election.
A substantial part of the Roman clergy rejected Felix’s arrangement and supported the deacon Dioscorus. Another group remained with Boniface. Both men were consecrated, creating a papal schism almost immediately after Felix’s death.
Dioscorus appears to have commanded broad support among the Roman clergy, which helps explain why Felix’s attempt to impose Boniface had failed to produce consensus. The crisis might have become prolonged, but Dioscorus died unexpectedly on October 14, only weeks after the rival consecrations. Boniface was consequently left without a living competitor.
The aftermath remained bitter. Supporters of Dioscorus were required to condemn him, although a later pope, Agapetus I, rejected that procedure. The episode exposed unresolved questions about how a bishop of Rome should be chosen and about how far a reigning pope could shape the succession.
The controversy therefore became one of Felix’s most important historical legacies. His decision raised a question that would return repeatedly in later centuries: did the authority of a pope extend to determining the identity of the next pope, or did the right of election remain with the established electoral community?
Felix had tried to replace uncertainty with continuity. Instead, his action demonstrated why papal succession could not easily be reduced to the personal choice of an incumbent.
Death, Burial, and the Memory of Felix IV
Felix was buried at Saint Peter’s, where his epitaph remembered him in language of confidence that the righteous would inherit the heavenly kingdom. The Liber Pontificalis gives a somewhat different chronological tradition for the ending of his pontificate, one of several reasons modern reference works acknowledge uncertainty over his precise death date. The official Vatican chronology now gives September 20 or 22, 530.
Later Catholic tradition honored Felix as a saint, but his importance to religious history extends beyond his cult.
He had become pope through unusually direct royal intervention, yet strengthened the judicial authority of the Roman bishop over clergy. He supported reform in Gaul while maintaining correspondence with Caesarius of Arles. He participated in the theological process that led to the Council of Orange, one of the most influential Western statements on grace and free will. He intervened in the administration of Ravenna, regulated clergy and property, restored churches, and planted one of Christianity’s most impressive monumental statements directly inside the ancient Roman Forum.
Even his greatest failure proved historically revealing. His attempt to designate Boniface exposed competing understandings of papal authority, clerical election, aristocratic influence, and political power.
Why Pope Felix IV Matters
Felix IV’s pontificate captures a Roman Church standing between the ancient and medieval worlds.
The Western Roman Empire no longer existed, but Roman institutions, aristocratic families, senatorial authority, imperial architecture, and memories of the old political order remained everywhere. Italy was ruled by an Ostrogothic monarchy whose kings were Arians, while the population of Rome overwhelmingly belonged to the Nicene church. The emperor still ruled at Constantinople. Bishops in Gaul appealed to Rome. Clergy at Ravenna carried their disputes before the pope. Ancient imperial buildings in the Forum became Christian sanctuaries.
Felix operated in all of those worlds at once.
His church of Saints Cosmas and Damian may be the most fitting monument to his pontificate. An ancient Roman structure became a Christian basilica. Above its sanctuary, Christ appeared in glory while apostles and martyrs stood beside him. At the edge of the scene was Felix, carrying the church in his hands.
That image captures much of what his four-year papacy represented. Felix inherited a church still deeply entangled with Gothic kings, Roman senators, eastern emperors, ancient buildings, and competing clerical factions, but he also helped shape institutions and doctrines that would outlive every political power around him.
His pontificate was short. Its surviving evidence shows that it was anything but insignificant.
Sources & Further Reading
Liber Pontificalis. “Life of Felix IV.” In Le Liber Pontificalis, edited by Louis Duchesne, 1:279–280. Paris: Ernest Thorin, 1886. English translation in Louise Ropes Loomis, The Book of the Popes (Liber Pontificalis). New York: Columbia University Press, 1916, 138–140. https://archive.org/details/bookofpopesliber00loom
Liber Pontificalis. “Life of Boniface II.” In Le Liber Pontificalis, edited by Louis Duchesne. Vol. 1. Paris: Ernest Thorin, 1886. https://archive.org/details/duchesne01
Cassiodorus. Cassiodori Senatoris Variae. Edited by Theodor Mommsen. Monumenta Germaniae Historica, Auctores Antiquissimi 12. Berlin: Weidmann, 1894. Especially 8.15, 8.24, and 9.15.3. https://www.dmgh.de/mgh_auct_ant_12/index.htm
Felix IV. “Epistola ad Caesarium Arelatensem.” February 5, 528. In Patrologia Latina 65. https://la.wikisource.org/wiki/Epistolae_et_decreta_%28Felix_IV%29
Felix IV. “Constitutum Felicis IV de Ecclesia Ravennatensi.” Preserved in Agnellus of Ravenna, Liber Pontificalis Ecclesiae Ravennatis. https://la.wikisource.org/wiki/Epistolae_et_decreta_%28Felix_IV%29
Agnellus of Ravenna. Liber Pontificalis Ecclesiae Ravennatis. Ninth century. https://la.wikisource.org/wiki/Liber_Pontificalis_Ecclesiae_Ravennatis
“Concilium Arausicanum.” Second Council of Orange, 529. In Concilia Galliae, A. 511–A. 695, edited by Charles de Clercq, 53–69. Corpus Christianorum Series Latina 148A. Turnhout: Brepols, 1963. https://la.wikisource.org/wiki/Concilium_Arausicanum_%28529%29
de Clercq, Charles, ed. Concilia Galliae, A. 511–A. 695. Corpus Christianorum Series Latina 148A. Turnhout: Brepols, 1963. https://www.brepols.net/products/IS-9782503014838-1
Schwartz, Eduard, ed. Acta Conciliorum Oecumenicorum. Vol. 4, pt. 2. Berlin and Leipzig: Walter de Gruyter, 1914. Especially 96–98 for Felix IV’s succession documents. https://openlibrary.org/books/OL28401269M/Acta_conciliorum_oecumenicorum
Felix IV. “Praeceptum Papae Felicis.” In Acta Conciliorum Oecumenicorum, edited by Eduard Schwartz, 4.2:96–97. Berlin and Leipzig, 1914. https://openlibrary.org/books/OL28401269M/Acta_conciliorum_oecumenicorum
“Contestatio Senatus.” In Acta Conciliorum Oecumenicorum, edited by Eduard Schwartz, 4.2:96–98. Berlin and Leipzig, 1914. https://openlibrary.org/books/OL28401269M/Acta_conciliorum_oecumenicorum
Duchesne, Louis. “La succession du pape Félix IV.” Mélanges d’archéologie et d’histoire 3 (1883): 239–266. https://www.persee.fr/doc/mefr_0223-4874_1883_num_3_1_6442 Persée
Sansterre, Jean-Marie. “Felice IV, papa.” Dizionario Biografico degli Italiani. Vol. 46. Rome: Istituto della Enciclopedia Italiana, 1996. https://www.treccani.it/enciclopedia/papa-felice-iv_%28Dizionario-Biografico%29/ Treccani
Sansterre, Jean-Marie. “Felice IV, santo.” Enciclopedia dei Papi. Rome: Istituto della Enciclopedia Italiana, 2000. https://www.treccani.it/enciclopedia/santo-felice-iv_%28Enciclopedia-dei-Papi%29/ Treccani
Holy See. “Felix IV.” The Holy See. Accessed October 7, 2026. https://www.vatican.va/content/vatican/en/holy-father/felice-iv.html Vatican
Richards, Jeffrey. The Popes and the Papacy in the Early Middle Ages, 476–752. London: Routledge & Kegan Paul, 1979. https://books.google.com/books/about/The_Popes_and_the_Papacy_in_the_Early_Mi.html?id=tsE9AAAAIAAJ
Moorhead, John. The Popes and the Church of Rome in Late Antiquity. London: Routledge, 2015. https://www.routledge.com/The-Popes-and-the-Church-of-Rome-in-Late-Antiquity/Moorhead/p/book/9781138305779 Routledge
Moorhead, John. “On Becoming Pope in Late Antiquity.” Journal of Religious History 30, no. 3 (2006): 279–293. https://onlinelibrary.wiley.com/doi/10.1111/j.1467-9809.2006.00494.x
Noble, Thomas F. X. “Theodoric and the Papacy.” In Teodorico il Grande e i Goti d’Italia. Spoleto: Centro Italiano di Studi sull’Alto Medioevo, 1993.
Pietri, Charles. “Aristocratie et société cléricale dans l’Italie chrétienne au temps d’Odoacre et de Théodoric.” Mélanges de l’École française de Rome 93 (1981): 417–467. https://www.persee.fr/collection/mefr
Caspar, Erich. Geschichte des Papsttums von den Anfängen bis zur Höhe der Weltherrschaft. Vol. 2. Tübingen: J. C. B. Mohr, 1933.
Harnack, Adolf von. “Der erste deutsche Papst (Bonifatius II., 530–32) und die beiden letzten Dekrete des römischen Senats.” Sitzungsberichte der Preussischen Akademie der Wissenschaften (1924): 24–42.
Cappuyns, M. “L’origine des ‘Capitula’ d’Orange 529.” Recherches de Théologie Ancienne et Médiévale 6 (1934): 121–142.
Pontal, Odette. Histoire des conciles mérovingiens. Paris: Éditions du Cerf, 1989. https://books.google.com/books/about/Histoire_des_conciles_m%C3%A9rovingiens.html?id=4yDZAAAAMAAJ
Tucci, Pier Luigi. The Temple of Peace in Rome. Cambridge: Cambridge University Press, 2017. Especially pt. 4, “AVLA DEI: The Basilica of Pope Felix IV (AD 526–530).” https://doi.org/10.1017/9781316795712 Cambridge University Press
Whitehead, Philip Barrows. “The Church of SS. Cosma e Damiano in Rome.” American Journal of Archaeology 31, no. 1 (1927): 1–18. https://penelope.uchicago.edu/Thayer/E/Journals/AJA/31/1/SS.Cosma_e_Damiano%2A.html Penelope
Brandenburg, Hugo. Ancient Churches of Rome from the Fourth to the Seventh Century: The Dawn of Christian Architecture in the West. Turnhout: Brepols, 2005.
Krautheimer, Richard. Rome: Profile of a City, 312–1308. Princeton, NJ: Princeton University Press, 1980.
Krautheimer, Richard, Spencer Corbett, and Wolfgang Frankl. Corpus Basilicarum Christianarum Romae: The Early Christian Basilicas of Rome (IV–IX Cent.). Vol. 1. Vatican City: Pontificio Istituto di Archeologia Cristiana, 1937. See 137–143 on SS. Cosmas and Damian.
Budriesi, Richard. La basilica dei Ss. Cosma e Damiano a Roma. Bologna, 1968.
Apollonj Ghetti, B. M. “Nuove considerazioni sulla basilica romana dei Ss. Cosma e Damiano.” Rivista di Archeologia Cristiana 50 (1974): 7–55.
Kitzinger, Ernst. Byzantine Art in the Making: Main Lines of Stylistic Development in Mediterranean Art, 3rd–7th Century. Cambridge, MA: Harvard University Press, 1977.
Ladner, Gerhart B. Die Papstbildnisse des Altertums und des Mittelalters. Vatican City: Pontificio Istituto di Archeologia Cristiana, 1941–1984.
Thunø, Erik. “Inscription and Divine Presence: Golden Letters in the Early Medieval Apse Mosaic.” Word & Image 27 (2011). https://www.tandfonline.com/doi/full/10.1080/02666286.2011.541122
Kelly, J. N. D., and Michael J. Walsh. The Oxford Dictionary of Popes. 2nd ed. Oxford: Oxford University Press, 2010.
Kirsch, Johann Peter. “Pope St. Felix IV.” In The Catholic Encyclopedia. Vol. 6. New York: Robert Appleton Company, 1909. https://www.newadvent.org/cathen/06031a.htm
“Felix IV (III), Pope, St.” New Catholic Encyclopedia. https://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/felix-iv-iii-pope-st
Inscriptiones Christianae Urbis Romae Septimo Saeculo Antiquiores. Nova Series, vol. 2, no. 4152. Vatican City: Pontificio Istituto di Archeologia Cristiana. Felix IV’s funerary inscription.
Inscriptiones Latinae Christianae Veteres. No. 1784. Dedication inscription of the Basilica of Saints Cosmas and Damian.