Eusebius of Caesarea

Eusebius was born around 260 AD, probably in Palestine. He studied under the scholar Pamphilus at Caesarea Maritima, inherited Pamphilus' great library, and became bishop of Caesarea around 313 AD. He survived the Great Persecution, attended the Council of Nicaea in 325, and died around 339.

His Ecclesiastical History (Historia Ecclesiastica) in ten books is the foundational work of church history — the first systematic attempt to trace the development of Christianity from the apostles to the early fourth century. Eusebius had access to sources now lost: letters, edicts, martyr acts, and earlier chronicles. He quotes them extensively, sometimes at enormous length, which makes his work invaluable even where his own judgement is questionable.

Eusebius was not a detached historian. He was a partisan of the emperor Constantine, whom he saw as God's instrument for the triumph of the Church. His narrative is providential: history moves toward the Christian empire. This bias is obvious and must be read critically. But no other ancient author preserves so much primary source material for the first three centuries of Christianity. The Ecclesiastical History remains indispensable.