Eusebius of Caesarea

Eusebius was born about 260, probably in Palestine, and attached himself as a young man to Pamphilus, the priest and scholar who ran the library at Caesarea. That library, built on the collection Origen had left there, was the best in the Christian world, and Eusebius spent his life inside it. He loved Pamphilus so much that he called himself Eusebius of Pamphilus for the rest of his days.

The Great Persecution under Diocletian caught them. Pamphilus was imprisoned for two years and beheaded in 310. Eusebius saw executions in Palestine, Tyre and Egypt, and wrote them down in The Martyrs of Palestine. He was himself imprisoned in Egypt and survived, and years later a confessor named Potamon publicly asked him how he had managed that. He never answered.

About 314 he became bishop of Caesarea. But his work is the books.

The Ecclesiastical History, in ten volumes, is the first history of the Christian church, and there is nothing else like it. Eusebius set out to trace the succession of bishops, the writers, the heretics, the sufferings of the Jews, and the martyrs, and he did it by quoting his sources at length. Whole passages of Papias, Hegesippus, Dionysius of Corinth, Clement, Irenaeus and dozens of others survive only because Eusebius copied them into his book before the originals were lost. Every history of early Christianity ever written depends on it.

He wrote much more: the Chronicle, a synchronized timeline of world history; the Preparation and the Demonstration of the Gospel, a two-part apologetic; the Onomasticon, a gazetteer of biblical place-names; a commentary on the Psalms and on Isaiah; and the Life of Constantine. He devised the Eusebian Canons, the marginal tables that let a reader find the parallel passages across the four gospels, and they are still printed in critical editions of the Greek New Testament. When Constantine ordered fifty Bibles for the churches of his new capital, Eusebius produced them.

His theology is the hard part of his record. At Nicaea in 325 he offered his own baptismal creed as a starting point and signed the final creed with visible reluctance about the word homoousios. Afterward he sided repeatedly with the anti-Nicene party, and he took part in the councils that deposed Eustathius of Antioch and Athanasius. He was a courtier to Constantine and wrote about him in terms that later readers have found excessive.

He died about 339.

Sources: Eusebius of Caesarea, Ecclesiastical History and Life of Constantine (Nicene and Post-Nicene Fathers, 2nd series, vol. 1); Eusebius, The Martyrs of Palestine; Philip Schaff, History of the Christian Church, vol. III.