Eusebius of Caesarea (~275 – May 30, 339) (often called Eusebius Pamphili, "Eusebius [the friend of] Pamphilus") was a bishop of Caesarea in Palestine and is often referred to as the father of church history because of his work in recording the history of the early Christian church. He is also supposed to have found in the records of Edessa the letters purporting to be written back and forth by its king Abgar and Jesus Christ.
His exact date and place of birth are unknown, and little is known of his youth. He became acquainted with the presbyter Dorotheus in Antioch and probably received exegetical instruction from him. In 296 he was in Palestine and saw Constantine who visited the country with Diocletian. He was in Caesarea when Agapius was bishop and became friendly with Pamphilus, with whom he seems to have studied the text of the Bible, with the aid of Origen's Hexapla, and commentaries collected by Pamphilus, in an attempt to prepare a correct version.
In 307 Pamphilus was imprisoned, but Eusebius continued their project. The resulting defence of Origen, in which they had collaborated, was finished by Eusebius after the death of Pamphilus and sent to the martyrs in the mines of Phaeno in Egypt. Eusebius then seems to have gone to Tyre and later to Egypt, where he first suffered persecution. The charge that he obtained his liberty by sacrificing to the gods is unfounded.
Eusebius is next heard of as bishop of Caesarea. He succeeded Agapius, whose time of office is not known, but Eusebius must have become bishop soon after 313. Nothing is known about the early years of his tenure. When the Council of Nicaea met in 325, Eusebius was prominent in its transactions. He was not naturally a leader or a deep thinker, but as a very learned man and a famous author who enjoyed the special favour of the emperor, he came to the fore among the 300 members of the council. The confession which he proposed became the basis of the Nicene Creed.
Eusebius was involved in the further development of the Arian controversies. For instance, in the dispute with Eustathius of Antioch, who opposed the growing influence of Origen and his practice of an allegorical exegesis of scripture, seeing in his theology the roots of Arianism, Eusebius, an admirer of Origen, was reproached by Eustathius for deviating from the Nicene faith, and was charged in turn with Sabellianism. Eustathius was accused, condemned and deposed at a synod in Antioch. The people of Antioch rebelled against this action, while the anti-Eustathians proposed Eusebius as the new bishop, but he declined.
After Eustathius had been removed, the Eusebians proceeded against Athanasius of Alexandria, a much more dangerous opponent. In 334 he was summoned before a synod in Caesarea; he did not attend. In the following year he was again summoned before a synod in Tyre at which Eusebius presided. Athanasius, foreseeing the result, went to Constantinople to bring his cause before the emperor. Constantine called the bishops to his court, among them Eusebius. Athanasius was condemned and exiled at the end of 335. At the same synod, another opponent was successfully attacked. Marcellus of Ancyra had long opposed the Eusebians, and had protested against the reinstitution of Arius. He was accused of Sabellianism and deposed in 336. Constantine died the next year and Eusebius did not long survive him. Eusebius died (probably at Caesarea), in 340 at the latest and probably on May 30, 339.
Of the extensive literary activity of Eusebius, a relatively large portion has been preserved. Although posterity suspected him of Arianism, Eusebius had made himself indispensable by his method of authorship; his comprehensive and careful excerpts from original sources saved his successors the painstaking labor of research. Hence much has been preserved which otherwise would have been destroyed.
The literary productions of Eusebius reflect on the whole the course of his life. At first he occupied himself with works on Biblical criticism, under the influence of Pamphilus and probably of Dorotheus of the School of Antioch. Afterward the persecutions under Diocletian and Galerius directed his attention to the martyrs of his own time and the past. And this led him to the history of the whole Church and finally to the history of the world, which to him was only a preparation for ecclesiastical history.
Then followed the time of the Arian controversies, and dogmatic questions came into the foreground. Christianity at last found recognition by the State; and this brought new problems-- apologies of a different sort had to be prepared. Lastly, Eusebius, the court theologian, wrote eulogies in praise of the first Christian emperor. To all this activity must be added numerous writings of a miscellaneous nature, addresses, letters, and the like, and exegetical works which include both commentaries and treatises on Biblical archeology and extend over the whole of his life.
1. Works on Biblical Text Criticism
Pamphilus and Eusebius occupied themselves with the text criticism of the Septuagint text of the Old Testament and especially of the New Testament. An edition of the Septuagint seems to have been already prepared by Origen, which, according to Jerome, was revised and circulated by Eusebius and Pamphilus. For an easier survey of the material of the four Evangelists, Eusebius divided his edition of the New Testament into paragraphs and provided it with a synoptical table so that it might be easier to find the pericopes which belong together.
2. The "Chronicle"
The two greatest historical works of Eusebius are his "Chronicle" and his "Church History." The former (Greek, Pantodape historia, "Universal History") is divided into two parts. The first part (Greek, Chronographia, "Annals") purports to give an epitome of universal history from the sources, arranged according to nations. The second part (Greek, Chronikoi kanones, "Chronological Canons") attempts to furnish a synchronism of the historical material in parallel columns.
The work as a whole has been lost in the original, but it may be reconstructed from later chronographists of the Byzantine school who made excerpts from the work with untiring diligence, especially George Syncellus. The tables of the second part have been completely preserved in a Latin translation by Jerome, and both parts are still extant in an Armenian translation, but these translations do not possess great value on account of numerous interpolations. The "Chronicle" as preserved extends to the year 325. It was written before the "Church History."
3. The "Church History"
In his "Church History" or "Ecclesiastical History" (Historia Ecclesiastica), Eusebius attempted according to his own declaration (I, i. 1) to present the history of the Church from the apostles to his own time, with special regard to the following points:
(1) the successions of bishops in the principal sees;
(2) the history of Christian teachers;
(3) the history of heresies;
(4) the history of the Jews;
(5) the relations to the heathen;
(6) the martyrdoms.
He grouped his material according to the reigns of the emperors, presenting it as he found it in his sources. The contents are as follows:
Book i: detailed introduction, on Jesus Christ
Book ii: The history of the apostolic time to the capture of Jerusalem by Titus
Book iii: The following time to Trajan
Books iv and v: the second century
Book vi: The time from Severus to Decius
Book vii: extends to the outbreak of the persecution under Diocletian
Book viii: more of this persecution
Book ix: history to Constantine's victory over Maxentius in the West and over Maximinus in the East
Book x: The reestablishment of the churches and the rebellion and conquest of Licinius.
In its present form the work was brought to a conclusion before the death of Crispus (July, 326), and, since book x. is dedicated to Paulinus of Tyre who died before 325, at the end of 323 or in 324. This work required the most comprehensive preparatory studies, and it must have occupied him for years. His collection of martyrdoms of the older period may have been one of these preparatory studies.
The authenticity of Eusebius's "Church History" is beyond dispute. Every new discovery shows anew the conscientious, careful and intelligent use of the libraries of Caesarea and Jerusalem.
In one quote from Eusebius, he blames the calamities which befell the Jewish nation on the Jews' role in the death of Jesus. This quote has been used to attack both Jews and Christians. See Christianity and anti-Semitism.
"that from that time seditions and wars and mischievous plots followed each other in quick succession, and never ceased in the city and in all Judea until finally the siege of Vespasian overwhelmed them. Thus the divine vengeance overtook the Jews for the crimes which they dared to commit against Christ. " (Eusebius of Caesarea, Church History: Book II, Chapter 6: The Misfortunes which overwhelmed the Jews after their Presumption against Christ)  (http://web.cbn.org/bibleresources/theology/eusebius/churchhistory/eusebius-b2-7.asp)
4. Life of Constantine (Vita Constantini) is a eulogy and therefore its style and selection of facts are affected by its purpose, rendering it inadequate as a continuation of the Church History. As the historian Socrates Scholasticus said, at the opening of his history that was designed as a continuation of Eusebius, "Also in writing the life of Constantine, this same author has but slightly treated of matters regarding Arius, being more intent on the rhetorical finish of his composition and the praises of the emperor, than on an accurate statement of facts."
5. Minor Historical Works
Before he compiled his church history, Eusebius edited a collection of martyrdoms of the earlier period and a biography of Pamphilus. The martyrology has not survived as a whole, but it has been preserved almost completely in parts. It contained:
(1) an epistle of the congregation of Smyrna concerning the martyrdom of Polycarp;
(2) the martyrdom of Pionius;
(3) the martyrdoms of Carpus, Papylus, and Agathonike;
(4) the martyrdoms in the congregations of Vienne and Lyons;
(5) the martyrdom of Apollonius.
Of the life of Pamphilus only a fragment survives. A work on the martyrs of Palestine in the time of Diocletian was composed after 311; numerous fragments are scattered in legendaries which still have to be collected. The life of Constantine was compiled after the death of the emperor and the election of his sons as Augusti (337). It is more a rhetorical eulogy on the emperor than a history, but is of great value on account of numerous documents incorporated in it.
5. Apologetic and Dogmatic Works
To the class of apologetic and dogmatic works belong:
(1) the "Apology for Origen," the first five books of which, according to the definite statement of Photius, were written by Pamphilus in prison, with the assistance of Eusebius. Eusebius added the sixth book after the death of Pamphilus. We possess only a Latin translation of the first book, made by Rufinus;
(2) a treatise against Hierocles (a Roman governor and Neoplatonic philosopher), in which Eusebius combated the former's glorification of Apollonius of Tyana in a work entitled "A Truth-loving Discourse " (Greek, Philalethes logos);
(3)Praeparatio evangelica ('Preparation for the Gospel'), commonly known by its Latin title, which attempts to prove the excellence of Christianity over every pagan religion and philiosphy. The Praeparatio consists of fifteen books which have been completely perserved. Eusebius considered it an introduction to Christianity for heathen. But its value for many later readers is more because Eusebius studded this work with so many fascinating and lively fragments from historians and philosphers which are nowhere else preserved. Here alone is preserved a summary of the writings of the Phoenician priest Sanchuniathon of which the accuracy has been shown by the mythological accounts found on the Ugaritic tables, here alone is the account from Diodorus Siculus's sixth book of Euhemerus' wondrous voyage to the island of Panchaea where Euhemerus purports to have found his true history of the gods, and almost here alone is preserved writings of the neo-Platonist philospher Atticus along with so much else.
(4)Demonstratio evangelica ('Proof of the Gospel') is closely connected to the Praeparatio and comprised originally twenty books of which ten have been completely preserved as well as a fragment of the fifteenth. Here Eusebius treats of the person of Jesus Christ. The work was probably finished before 311;
(5) another work which originated in the time of the persecution, entitled "Prophetic Extracts" (Eklogai prophetikai). It discusses in four books the Messianic texts of Scripture;
(6) the treatise "On Divine Manifestation" (Peri theophaneias), dating from a much later time. It treats of the incarnation of the Divine Logos, and its contents are in many cases identical with the Demonstratio evangelica. Only fragments are preserved;
(7) the polemical treatise "Against Marcellus," dating from about 337;
(8) a supplement to the last-named work, entitled "On the Theology of the Church," in which he defended the Nicene doctrine of the Logos against the party of Athanasius.
A number of writings, belonging in this category, have been entirely lost.
6. Exegetical and Miscellaneous Works.
Of the exegetical works of Eusebius nothing has been preserved in its original form. The so-called commentaries are based upon late manuscripts copied from fragments of catenae. A more comprehensive work of an exegetical nature, preserved only in fragments, is entitled "On the Differences of the Gospels" and was written for the purpose of harmonizing the contradictions in the reports of the different Evangelists. It was also for exegetical purposes that Eusebius wrote his treatises on Biblical archeology:
(1) a work on the Greek equivalents of Hebrew Gentilic nouns;
(2) a description of old Judea with an account of the lots of the ten tribes;
(3) a plan of Jerusalem and the Temple of Solomon.
These three treatises have been lost. A work entitled "On the Names of Places in the Holy Scriptures," an alphabetical list of place names, is still in existence. Further mention is to be made of addresses and sermons some of which have been preserved, e.g., a sermon on the consecration of the church in Tyre, and an address on the thirtieth anniversary of the reign of Constantine (336). Of the letters of Eusebius only a few fragments are extant.
III. Estimate of Eusebius
1. His Doctrine.
From a dogmatic point of view, Eusebius stands entirely upon the shoulders of Origen. Like Origen, he started from the fundamental thought of the absolute sovereignty (monarchia) of God. God is the cause of all beings. But he is not merely a cause; in him everything good is included, from him all life originates, and he is the source of all virtue. He is the highest God to whom Christ is subject as the second God. God sent Christ into the world that it may partake of the blessings included in the essence of God. Christ is the only really good creature, he possesses the image of God and is a ray of the eternal light; but the figure of the ray is so limited by Eusebius that he expressly emphasizes the self-existence of Jesus.
Eusebius was intent upon emphasizing the difference of the persona of the Trinity and maintaining the subordination of Jesus to God (he never calls him theos) because in all contrary attempts he suspected polytheism or Sabellianism. Jesus is a creature of God whose generation, it is true, took place before time. Jesus is in his activity the organ of God, the creator of life, the principle of every revelation of God, who in his absoluteness is enthroned above all the world. This divine Logos assumed a human body without being altered thereby in any way in his being. The relation of the Holy Spirit within the Trinity Eusebius explained similarly to that of the Son to the Father. No point of this doctrine is original with Eusebius, all is traceable to his teacher Origen. The lack of originality in his thinking shows itself in the fact that he never presented his thoughts in a system.
2. His Excellencies and Limitations
The limitations of Eusebius are closely connected with his gifts. His time justly considered him its most learned man. A list of the sources he used for his church history would show what an amount of work had to be done to elaborate and sift the mass of material. But the learning of Eusebius can not be measured with that of Origen. Origen was a productive spirit, Eusebius a compiler. Eusebius, however, distinguished himself by his carefulness. A man like Eusebius was not without weight in the time when barbarian nations began to invade the Church in large masses. In the time which followed nobody excelled him in learning. Church historians were able to copy him, but they could not supply his place.