|First Council of Nicaea|
|Accepted by||Eastern Orthodoxy, Oriental Orthodoxy, Assyrian Church of the East, Roman Catholicism, Anglicanism, Lutheranism, Calvinism|
|Previous council||none considered ecumenical|
|Next council||First Council of Constantinople|
|Convoked by||Constantine I|
|Presided by||St. Alexander of Alexandria|
|Attendance||250–318 (only five from Western Church)|
|Topics of discussion||Arianism, celebration of Passover (Easter), Miletian schism, validity of baptism by heretics, lapsed Christians|
|Documents and statements||Original Nicene Creed and about 20 decrees|
|Chronological list of Ecumenical councils|
The First Council of Nicea was convened in Nicaea in Bithynia (present-day İznik in Turkey) by the Roman Emperor Constantine I in AD 325. The Council was historically significant as the first effort to attain consensus in the church through an assembly representing all of Christendom. 
The First Council of Nicea is believed to have been the first Ecumenical council of the Christian Church. Most significantly, it resulted in the first uniform Christian doctrine, called the Nicene Creed. With the creation of the creed, a precedent was established for subsequent general (ecumenical) councils of Bishops' (Synods) to create statements of belief and canons of doctrinal orthodoxy— the intent being to define unity of beliefs for the whole of Christendom.
Derived from Greek oikoumenikos, "ecumenical" literally means worldwide but generally is assumed to be limited to the Roman Empire, as in Augustus' claim to be ruler of the oikoumene/world; the earliest extant uses of the term for a council are Eusebius' Life of Constantine 3.6 around 338 "σύνοδον οἰκουμενικὴν συνεκρότει" (he convoked an Ecumenical council), Athanasius' Ad Afros Epistola Synodica in 369, and the Letter in 382 to Pope Damasus I and the Latin bishops from the First Council of Constantinople.
The purpose of the council was to resolve disagreements arising from within the Church of Alexandria over the nature of Jesus in relationship to the Father; in particular, whether Jesus was the literal son of God or was he a figurative son, like the other "sons of God" in the Bible. St. Alexander of Alexandria and Athanasius took the first position; the popular presbyter Arius, from whom the term Arian controversy comes, took the second. The council decided against the Arians overwhelmingly (of the estimated 250–318 attendees, all but two voted against Arius). In Ammianus Marcellinus's words,
|“||The enmity of the Christians towards each other surpassed the fury of savage beasts against man||”|
Another result of the council was an agreement on when to celebrate the Resurrection, the most important feast of the ecclesiastical calendar. The council decided in favour of celebrating the resurrection on the first Sunday after the first full moon following the vernal equinox, independently of the Hebrew Calendar (see also Quartodecimanism and Easter controversy). It authorized the Bishop of Alexandria (presumably using the Alexandrian calendar) to announce annually the exact date to his fellow bishops.
Historically significant as the first effort to attain consensus in the church through an assembly representing all of Christendom, the Council was the first occasion for the development of technical Christology. Through it a precedent was set for subsequent general councils to adopt creeds and canons. This council is generally considered the beginning of the period of the First seven Ecumenical Councils in the History of Christianity.
Character and purpose
The First Council of Nicaea was convened by Constantine I upon the recommendations of a synod led by Hosius of Cordoba in the Eastertide of 325. This synod had been charged with investigation of the trouble brought about by the Arian controversy in the Greek-speaking east. To most bishops, the teachings of Arius were heretical and dangerous to the salvation of souls. In the summer of 325, the bishops of all provinces were summoned to Nicaea (now known as İznik, in modern-day Turkey), a place easily accessible to the majority of them, particularly those of Asia Minor, Syria, Palestine, Egypt, Greece, and Thrace.
Approximately 250 to 318 bishops attended, from every region of the Empire except Britain. Of the bishops whose successors would much later be termed Patriarchs (see Pentarchy), Alexander of Alexandria, Eustathius of Antioch, and Macarius of Jerusalem attended, and Sylvester I, Bishop of Rome, sent legates. Constantinople had not yet been founded. Another participant was the first church historian, Eusebius of Caesarea. Athanasius of Alexandria, famous for his battles against Arianism, was also present, but was then only a deacon.
This was the first general council in the history of the Church since the Apostolic Council of Jerusalem, which had established the conditions upon which Gentiles could join the Church. In the Council of Nicaea, “the Church had taken her first great step to define doctrine more precisely in response to a challenge from a heretical theology.” The writings and teachings of early church fathers presented even greater challenges for the Church in defining exactly what was considered the heretical theology prior to the First Council of Nicaea. Early Christian apologist Justin Martyr clearly presented his earlier teachings on the logos (Jesus relationship to Father) in the Dialogue with Trypho (Dialogue with Trypho, 56). The resolutions in the council, being ecumenical, were intended for the whole Church.
Constantine had invited all 1800 bishops of the Christian church (about 1000 in the east and 800 in the west), but a lesser and unknown number attended. Eusebius of Caesarea counted 250, Athanasius of Alexandria counted 318, and Eustathius of Antioch counted 270 (all three were present at the council). Later, Socrates Scholasticus recorded more than 300, and Evagrius, Hilarius, Jerome and Rufinus recorded 318.
The participating bishops were given free travel to and from their episcopal sees to the council, as well as lodging. These bishops did not travel alone; each one had permission to bring with him two priests and three deacons; so the total number of attendees would have been above 1,500. Eusebius speaks of an almost innumerable host of accompanying priests, deacons and acolytes.
The Eastern bishops formed the great majority. Of these, the first rank was held by the three patriarchs: Alexander of Alexandria, Eustathius of Antioch, and Macarius of Jerusalem. Many of the assembled fathers—for instance, Paphnutius of Thebes, Potamon of Heraclea and Paul of Neocaesarea—had stood forth as confessors of the faith and came to the council with the marks of persecution on their faces. Other remarkable attendees were Eusebius of Nicomedia; Eusebius of Caesarea; Nicholas of Myra; Aristakes of Armenia (son of Saint Gregory the Illuminator); Leontius of Caesarea; Jacob of Nisibis, a former hermit; Hypatius of Gangra; Protogenes of Sardica; Melitius of Sebastopolis; Achilleus of Larissa; Athanasius of Thessaly and Spyridion of Trimythous, who even while a bishop made his living as a shepherd. From foreign places came a Persian bishop John, a Gothic bishop Theophilus and Stratophilus, bishop of Pitiunt in Egrisi (located in the western part of modern-day Georgia outside of the Roman Empire).
The Latin-speaking provinces sent at least five representatives: Marcus of Calabria from Italia, Cecilian of Carthage from Africa, Hosius of Córdoba from Hispania, Nicasius of Dijon from Gaul, and Domnus of Stridon from the province of the Danube. Pope Silvester I declined to attend, pleading infirmity, but he was represented by two priests.
Athanasius of Alexandria, a young deacon and companion of Bishop Alexander of Alexandria, was among these assistants. Athanasius eventually spent most of his life battling against Arianism. Alexander of Constantinople, then a presbyter, was also present as representative of his aged bishop.
The supporters of Arius included Secundus of Ptolemais, Theonus of Marmarica, Zphyrius, and Dathes, all of whom hailed from Libya and the Pentapolis. Other supporters included Eusebius of Nicomedia, Eusebius of Caesarea, Paulinus of Tyrus, Actius of Lydda, Menophantus of Ephesus, and Theognus of Nicaea.
"Resplendent in purple and gold, Constantine made a ceremonial entrance at the opening of the council, probably in early June, but respectfully seated the bishops ahead of himself." As Eusebius described, Constantine "himself proceeded through the midst of the assembly, like some heavenly messenger of God, clothed in raiment which glittered as it were with rays of light, reflecting the glowing radiance of a purple robe, and adorned with the brilliant splendor of gold and precious stones." He was present as an observer, but he did not vote. Constantine organized the Council along the lines of the Roman Senate. "Ossius [Hosius] presided over its deliberations; he probably, and the two priests of Rome certainly, came as representatives of the Pope." “Eusebius of Nicomedia probably gave the welcoming address."
Agenda and procedure
The agenda of the synod were:
- The Arian question regarding the relationship between God the Father and Jesus; i.e. are the Father and Son one in purpose only or also one in being;
- The date of celebration of the Paschal/Easter observation
- The Meletian schism;
- The validity of baptism by heretics;
- The status of the lapsed in the persecution under Licinius.
The council was formally opened May 20, in the central structure of the imperial palace, with preliminary discussions on the Arian question. In these discussions, some dominant figures were Arius, with several adherents. "Some 22 of the bishops at the council, led by Eusebius of Nicomedia, came as supporters of Arius. But when some of the more shocking passages from his writings were read, they were almost universally seen as blasphemous." Bishops Theognis of Nicaea and Maris of Chalcedon were among the initial supporters of Arius.
Eusebius of Caesarea called to mind the baptismal creed (symbol) of his own diocese at Caesarea in Palestine, as a form of reconciliation. The majority of the bishops agreed. For some time, scholars thought that the original Nicene Creed was based on this statement of Eusebius. Today, most scholars think that this Creed is derived from the baptismal creed of Jerusalem, as Hans Lietzmann proposed. Another possibility is the Apostle's Creed.
In any case, as the council went on, the orthodox bishops won approval of every one of their proposals. After being in session for an entire month, the council promulgated on June 19 the original Nicene Creed. This profession of faith was adopted by all the bishops "but two from Libya who had been closely associated with Arius from the beginning." No historical record of their dissent actually exists; the signatures of these bishops are simply absent from the creed.
The Arian controversy was a Christological dispute that began in Alexandria between the followers of Arius (the Arians) and the followers of St. Alexander of Alexandria (now known as Homoousians). Alexander and his followers believed that the Son was of the same substance as the Father, co-eternal with him. The Arians believed that they were different and that the Son, though he may be the most perfect of creations, was only a creation. A third group (now known as Homoiousians) later tried to make a compromise position, saying that the Father and the Son were of similar substance.
Much of the debate hinged on the difference between being "born" or "created" and being "begotten". Arians saw these as the same; followers of Alexander did not. Indeed, the exact meaning of many of the words used in the debates at Nicaea were still unclear to speakers of other languages. Greek words like "essence" (ousia), "substance" (hypostasis), "nature" (physis), "person" (prosopon) bore a variety of meanings drawn from pre-Christian philosophers, which could not but entail misunderstandings until they were cleared up. The word homoousia, in particular, was initially disliked by many bishops because of its associations with Gnostic heretics (who used it in their theology), and because it had been condemned at the 264–268 Synods of Antioch.
Homoousians believed that to follow the Arian view destroyed the unity of the Godhead, and made the Son unequal to the Father, in contravention of the Scriptures ("The Father and I are one", ). Arians, on the other hand, believed that since God the Father created the Son, he must have emanated from the Father, and thus be lesser than the Father, in that the Father is eternal, but the Son was created afterward and, thus, is not eternal. The Arians likewise appealed to Scripture, quoting verses such as : "the Father is greater than I". Homoousians countered the Arians' argument, saying that the Father's fatherhood, like all of his attributes, is eternal. Thus, the Father was always a father, and that the Son, therefore, always existed with him.
The Council declared that the Father and the Son are of the same substance and are co-eternal, basing the declaration in the claim that this was a formulation of traditional Christian belief handed down from the Apostles. This belief was expressed in the Nicene Creed.
The Nicene Creed
By and large, many creeds were acceptable to the members of the council. From his perspective, even Arius could cite such a creed.
For Bishop Alexander and others, however, greater clarity was required. Some distinctive elements in the Nicene Creed, perhaps from the hand of Hosius of Cordova, were added.
- Jesus Christ is described as "God from God, Light from Light, true God from true God," confirming his divinity. When all light sources were natural, the essence of light was considered to be identical, regardless of its form.
- Jesus Christ is said to be "begotten, not made", asserting his co-eternalness with God, and confirming it by stating his role in the Creation. Basically, they were saying that Jesus was God, and God's son, not a creation of God. This is considered one of the mysteries of the Catholic Church.
- Finally, he is said to be "from the substance of the Father," in direct opposition to Arianism. Some ascribe the term Consubstantial, i.e., "of the same substance" (of the Father), to Constantine who, on this particular point, may have chosen to exercise his authority.
Of the third article only the words "and in the Holy Spirit" were left; the original Nicene Creed ended with these words. Then followed immediately the canons of the council. Thus, instead of a baptismal creed acceptable to both the homoousian and Arian parties, as proposed by Eusebius, the council promulgated one which was unambiguous in the aspects touching upon the points of contention between these two positions, and one which was incompatible with the beliefs of Arians. From earliest times, various creeds served as a means of identification for Christians, as a means of inclusion and recognition, especially at baptism. In Rome, for example, the Apostles' Creed was popular, especially for use in Lent and the Easter season. In the Council of Nicaea, one specific creed was used to define the Church's faith clearly, to include those who professed it, and to exclude those who did not.
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The text of this profession of faith is preserved in a letter of Eusebius to his congregation, in Athanasius, and elsewhere. Although the most vocal of anti-Arians, the Homoousians (from the Koine Greek word translated as "of same substance" which was condemned at the Council of Antioch in 264–268), were in the minority, the Creed was accepted by the council as an expression of the bishops' common faith and the ancient faith of the whole Church.
Bishop Hosius of Cordova, one of the firm Homoousians, may well have helped bring the council to consensus. At the time of the council, he was the confidant of the emperor in all Church matters. Hosius stands at the head of the lists of bishops, and Athanasius ascribes to him the actual formulation of the creed. Great leaders such as Eustathius of Antioch, Alexander of Alexandria, Athanasius, and Marcellus of Ancyra all adhered to the Homoousian position.
In spite of his sympathy for Arius, Eusebius of Caesarea adhered to the decisions of the council, accepting the entire creed. The initial number of bishops supporting Arius was small. After a month of discussion, on June 19, there were only two left: Theonas of Marmarica in Libya, and Secundus of Ptolemais. Maris of Chalcedon, who initially supported Arianism, agreed to the whole creed. Similarly, Eusebius of Nicomedia and Theognis of Nice also agreed, except for the certain statements.
The emperor carried out his earlier statement: everybody who refuses to endorse the Creed will be exiled. Arius, Theonas, and Secundus refused to adhere to the creed, and were thus exiled to Illyria, in addition to being excommunicated. The works of Arius were ordered to be confiscated and consigned to the flames while all persons found possessing them were to be executed. Nevertheless, the controversy, already festering, continued in various parts of the empire.
Separation of Easter computation from Jewish calendar
After the June 19 settlement of the most important topic, the question of the date of the Christian Passover (Easter) was brought up. This feast is linked to the Jewish Passover and Feast of Unleavened Bread, as the crucifixion and resurrection of Jesus occurred at the time of those observances. Traditionally, Christians had set Easter to a Sunday in the lunar month of Nisan. To determine which lunar month was to be designated as Nisan, Christians relied on the Jewish community. By the later 3rd century, however, some Christians began to express dissatisfaction with what they took to be the disorderly state of the Jewish calendar. These Christians argued that contemporary Jews were identifying the wrong lunar month as the month of Nisan, choosing a month whose 14th day fell before the spring equinox. Christians, these thinkers argued, should abandon the custom of relying on Jewish informants and instead do their own computations to determine which month should be styled Nisan, setting the Easter festival within this independently-computed, Christian Nisan, which would always locate the festival after the equinox. They justified this break with tradition by arguing that it was in fact the contemporary Jewish calendar that had broken with tradition by ignoring the equinox, and that in former times the 14th of Nisan had never preceded the equinox. Others, however, felt that the customary practice of reliance on the Jewish calendar should continue, even if the Jewish computations were in error from a Christian point of view. 
The controversy between those who argued for independent computations, and those who argued for continued reliance on the Jewish calendar, was formally resolved by the Council, which endorsed the independent procedure that had been in use for some time at Rome and Alexandria. Easter was henceforward to be a Sunday in a lunar month chosen according to Christian criteria--in effect, a Christian Nisan-- not in the month of Nisan as defined by Jews. Those who argued for continued reliance on the Jewish calendar (called "protopaschites" by later historians) were urged to come around to the majority position. That they did not all immediately do so is revealed by the existence of sermons, canons, and tracts written against the protopaschite practice in the later 4th century.
These two rules, independence of the Jewish calendar and worldwide uniformity, were the only rules for Easter explicitly laid down by the Council. No details for the computation were specified; these were worked out in practice, a process that took centuries and generated a number of controversies. (See also Computus and Reform of the date of Easter.) In particular, the Council did not decree that Easter must fall on Sunday. This was already the practice almost everywhere. Nor did the Council decree that Easter must never coincide with Nisan 15 (the first Day of Unleavened Bread, now commonly called "Passover") in the Hebrew calendar. By endorsing the move to independent computations, the Council had separated the Easter computation from all dependence, positive or negative, on the Jewish calendar. The "Zonaras proviso", the claim that Easter must always follow Nisan 15 in the Hebrew calendar, was not formulated until after some centuries the accumulation of errors in the Julian solar and lunar calendars had made it the de-facto state of affairs that Julian Easter always followed Hebrew Nisan 15.
The suppression of the Meletian schism was one of the three important matters that came before the Council of Nicaea. Meletius, it was decided, should remain in his own city of Lycopolis, but without exercising authority or the power to ordain new clergy; moreover he was forbidden to go into the environs of the town or to enter another diocese for the purpose of ordaining its subjects. Melitius retained his episcopal title, but the ecclesiastics ordained by him were to receive again the imposition of hands, the ordinations performed by Meletius being therefore regarded as invalid. Clergy ordained by Meletius were ordered to yield precedence to those ordained by Alexander, and they were not to do anything without the consent of Bishop Alexander.
In the event of the death of a non-Meletian bishop or ecclesiastic, the vacant see might be given to a Meletian, provided he were worthy and the popular election were ratified by Alexander. As to Meletius himself, episcopal rights and prerogatives were taken from him. These mild measures, however, were in vain; the Meletians joined the Arians and caused more dissension than ever, being among the worst enemies of Athanasius. The Meletians ultimately died out around the middle of the fifth century.
Finally, the council promulgated twenty new church laws, called canons, (though the exact number is subject to debate), that is, unchanging rules of discipline. The twenty as listed in the Nicene and Post-Nicene Fathers are as follows:
- 1. prohibition of self-castration; (see Origen)
- 2. establishment of a minimum term for catechumen;
- 3. prohibition of the presence in the house of a cleric of a younger woman who might bring him under suspicion;
- 4. ordination of a bishop in the presence of at least three provincial bishops and confirmation by the metropolitan;
- 5. provision for two provincial synods to be held annually;
- 6. exceptional authority acknowledged for the patriarchs of Alexandria and Rome, for their respective regions;
- 7. recognition of the honorary rights of the see of Jerusalem;
- 8. provision for agreement with the Novatianists;
- 9–14. provision for mild procedure against the lapsed during the persecution under Licinius;
- 15–16. prohibition of the removal of priests;
- 17. prohibition of usury among the clergy;
- 18. precedence of bishops and presbyters before deacons in receiving Holy Communion, the Eucharist;
- 19. declaration of the invalidity of baptism by Paulian heretics;
- 20. prohibition of kneeling during the liturgy, on Sundays and in the fifty days of Eastertide ("the pentecost"). Standing was the normative posture for prayer at this time, as it still is among the Eastern Orthodox and Eastern Catholics. (In time, Western Christianity adopted the term Pentecost to refer to the last Sunday of Eastertide, the fiftieth day.)
On July 25, 325, in conclusion, the fathers of the council celebrated the emperor's twentieth anniversary. In his valedictory address, Constantine again informed his hearers how averse he was to dogmatic controversy; he wanted the Church to live in harmony and peace. In a circular letter, he announced the accomplished unity of practice by the whole Church in the date of the celebration of Christian Passover (now called Easter).
Effects of the Council
The long-term effects of the Council of Nicaea were significant. For the first time, representatives of many of the bishops of the Church convened to agree on a doctrinal statement. Also for the first time, the Emperor played a role, by calling together the bishops under his authority, and using the power of the state to give the Council's orders effect.
In the short-term, however, the council did not completely solve the problems it was convened to discuss and a period of conflict and upheaval continued for some time. Constantine himself was succeeded by two Arian Emperors in the Eastern Empire: his son, Constantine II and Valens. Valens could not resolve the outstanding ecclesiastical issues, and unsuccessfully confronted St. Basil over the Nicene Creed. Pagan powers within the Empire sought to maintain and at times re-establish Paganism into the seat of Emperor (see Arbogast and Julian the Apostate). Arians and the Meletians soon regained nearly all of the rights they had lost, and consequently, Arianism continued to spread and to cause division in the Church during the remainder of the fourth century. Almost immediately, Eusebius of Nicomedia, an Arian bishop and cousin to Constantine I, used his influence at court to sway Constantine's favor from the orthodox Nicene bishops to the Arians. Eustathius of Antioch was deposed and exiled in 330. Athanasius, who had succeeded Alexander as Bishop of Alexandria, was deposed by the First Synod of Tyre in 335 and Marcellus of Ancyra followed him in 336. Arius himself returned to Constantinople to be readmitted into the Church, but died shortly before he could be received. Constantine died the next year, after finally receiving baptism from Arian Bishop Eusebius of Nicomedia, and "with his passing the first round in the battle after the Council of Nicaea was ended."
- Eusebius of Caesarea, Letter of Eusebius of Cæsarea to the people of his Diocese Account of the Council of Nicea; The Life of the Blessed Emperor Constantine Book 3, Chapters VI-XXI treat the First Council of Nicaea.
- Athanasius of Alexandria, Defence of the Nicene Definition; Ad Afros Epistola Synodica
- Eustathius of Antioch, Letter recorded in Theodoret H.E. 1.7
- Socrates, Of the Synod which was held at Nicæa in Bithynia, and the Creed there put forth Book 1 Chapter 8 of his Ecclesiastical History, 5th century source.
- Sozomen, Of the Council convened at Nicæa on Account of Arius Book 1 Chapter 17 of his Ecclesiastical History, a 5th century source.
- Theodoret, General Council of Nicæa Book 1 Chapter 6 of his Ecclesiastical History; The Epistle of the Emperor Constantine, concerning the matters transacted at the Council, addressed to those Bishops who were not present Book 1 Chapter 9 of his Ecclesiastical History, a 5th century source;
- Philostorgius, Epitome of the Church History.
- Ayres, Lewis, Nicaea and Its Legacy, 2004.
- Carroll, Warren H., The Building of Christendom, 1987, ISBN 0-931888-24-7
- Davis, S.J., Leo Donald, The First Seven Ecumenical Councils (325-787), 1983, ISBN 0-8146-5616-1
- Kelly, J.N.D., The Nicene Crisis in Early Christian Doctrines, 1978, ISBN 0-06-064334-X
- Kelly, J.N.D., The Creed of Nicea in Early Christian Creeds, 1982, ISBN 0-582-49219-X
- Newman, John Henry., The Ecumenical Council of Nicæa in the Reign of Constantine from Arians of the Fourth Century, 1871
- Rubenstein, Richard E., When Jesus Became God: The Epic Fight Over Christ's Divinity in the Last Days of Rome, 2003, ISBN 0-15-100368-8
- Rusch, William G. "The Trinitarian Controversy", Sources of Christian Thought Series, ISBN 0-8006-1410-0
- Schaff, Philip The first ecumenical council includes creed and canons of the council.
- Tanner S.J., Norman P., "The Councils of the Church: A Short History", 2001, ISBN 0-8245-1904-3
- Richard Kieckhefer (1989). "Papacy". Dictionary of the Middle Ages. ISBN 0-684-18275-0. Cite error: Invalid
<ref>tag; name "dictionary" defined multiple times with different content
- Winkelmann, F, ed. (1975) (in Template:El), Vita Constantini, Berlin, DE: Akademie-Verlag, http://khazarzar.skeptik.net/books/eusebius/vc/gr/
- Schaff, Philip; Knight, Kevin, eds. (1892) , Archibald Robertson (transl.), "Ad Afros Epistola Synodica", Nicene and Post-Nicene Fathers, Second Series, Vol. 4. (Buffalo, NY: Christian Literature Publishing Co), http://www.newadvent.org/fathers/2819.htm
- The Seven Ecumenical Councils, Christian Classics Ethæreal Library, http://www.ccel.org/fathers2/NPNF2-14/Npnf2-14-63.htm
- Schaff's History of the Christian Church, Volume III, Nicene and Post-Nicene Christianity, § 120. The Council of Nicaea, 325: "Only two Egyptian bishops, Theonas and Secundus, persistently refused to sign, and were banished with Arius to Illyria. The books of Arius were burned and his followers branded as enemies of Christianity."
- Carroll, 10
- Carroll, 11
- Carroll, 12
- Eusebius of Caesaria. "Life of Constantine (Book III)". pp. Chapter 9. http://www.newadvent.org/fathers/25023.htm. Retrieved 2006-05-08.
- Ad Afros Epistola Synodica 2
- Theodoret H.E. 1.7
- H.E. 1.8
- H.E. 3.31
- Contra Constantium
- Atiya, Aziz S.. The Coptic Encyclopedia. New York:Macmillan Publishing Company, 1991. ISBN 0-02-897025-X.
- Atiya, Aziz S.. The Coptic Encyclopedia. New York:Macmillan Publishing Company, 1991. ISBN 0-02-897025-X.
- Philostorgius, in Photius, Epitome of the Ecclesiastical History of Philostorgius, book 1, chapter 9.
- Philostorgius, in Photius, Epitome of the Ecclesiastical History of Philostorgius, book 1, chapter 9.
- Eusebius, The Life of the Blessed Emperor Constantine, Book 3, Chapter 10.
- Original lists of attendees can be found in Patrum Nicaenorum nomina Latine, Graece, Coptice, Syriace, Arabice, Armeniace, ed. Henricus Gelzer, Henricus Hilgenfeld, Otto Cuntz. 2nd edition. (Stuttgart: Teubner, 1995)
- Catholic Encyclopedia: Arianism: "And a new party had arisen, the strict and pious Homoiousians, not friends of Athanasius, nor willing to subscribe to the Nicene terms, yet slowly drawing nearer to the true creed and finally accepting it. In the councils which now follow these good men play their part."
- "Socrates Church History Chapter IX". http://www.ccel.org/ccel/schaff/npnf202.ii.iv.ix.html.
- "Those who place [the first lunar month of the year] in [the twelfth zodiacal sign before the spring equinox] and fix the Paschal fourteenth day accordingly, make a great and indeed an extraordinary mistake", Anatolius of Laodicea, quoted in Eusebius, Church History 7.32.
- "On the fourteenth day of [the month], being accurately observed after the equinox, the ancients celebrated the Passover, according to the divine command. Whereas the men of the present day now celebrate it before the equinox, and that altogether through negligence and error", Peter, Bishop of Alexandria, quoted in the Chronicon Paschale
- A version of the Apostolic Constitutions used by the sect of the Audiani advised: "Do not do your own computations, but instead observe Passover when your brethren from the circumcision do. If they err [in the computation], it is no matter to you...." Epiphanius, Panarion 3.1.10 (Heresy #70, 10,1), PG 42,355-360. Frank Williams, ed., The Panarion of Epiphanius of Salamis Books II and III, Leiden, E.J. Brill, 1994, p. 412. Also quoted in Margaret Dunlop Gibson, The Didascalia Apostolorum in Syriac, London, 1903, p. vii.
- St. John Chrysostom, "Against those who keep the first Passover", in Saint John Chrysostom: Discourses against Judaizing Christians, translated by Paul W. Harkins, Washington, D.C., 1979, p. 47ff.
- Apostolic Canon 7: If any bishop, presbyter, or deacon shall celebrate the holy day of Easter before the vernal equinox with the Jews, let him be deposed. A Select Library of Nicene and Post-Nicene Fathers of the Christian Church, Second Series, Volume 14: The Seven Ecumenical Councils, Eerdmans, 1956, p. 594
- Epiphanius of Salamis, "Against the Audians", Panairion 3.1 (Heresy #70), PG 42, 339. Frank Williams, ed., The Panarion of Epiphanius of Salamis Books II and III, Leiden, 1994, p. 402.
- The Quartodeciman practice recorded by Eusebius in the late 2nd century, if it still existed at the time of the Council, is not known to have been followed outside the Roman Province of Asia. The Pepuzites, or "solar quartodecimans", held Easter on the Sunday falling in the week of April 6th, Sozomen, Church History, 7.18.
- Peter L'Huillier, The Church of the Ancient Councils, St. Vladimir's Seminary Press, Crestwood, 1996, p. 25.
- "Meletius" in the 1913 Catholic Encyclopedia.
- "Nicene and Post-Nicene Fathers, Series II, Vol. XIV, Excursus on the Number of the Nicene Canons". Early Church Fathers. http://www.ccel.org/fathers2/NPNF2-14/Npnf2-14-24.htm#TopOfPage. Retrieved 2006-05-08.
- "Nicene and Post-Nicene Fathers, Series II, Vol. XIV, The Canons of the 318 Holy Fathers Assembled in the City of Nice (sic), in Bithynia.". Early Church Fathers. http://www.ccel.org/fathers2/NPNF2-14/Npnf2-14-13.htm#P561_131414. Retrieved 2006-05-08.
- For the exact text of the prohibition of kneeling, in Greek and in English translation, see canon 20 of the acts of the council.
- "Heroes of the Fourth Century". http://www.orthodoxresearchinstitute.org/articles/patrology/heroes_of_4th_century_pt2.htm.
- Leo Donald Davis, S.J., "The First Seven Ecumenical Councils (325-787)", 77, ISBN 0-8146-5616-1
1911 Encyclopædia Britannica]