Eusebius was born in the early 260s, probably in Caesarea, which was to be the centre of his activities for most of his life. He became bishop of Caesarea in about 313 (probably in succession to Agapius, who had ordained him priest and seems to have survived the Great Persecution), and died on 30 May 339. We know comparatively little about his life: a Life was written by his successor at Caesarea, Acacius, but this has been lost. This is doubtless because, though posterity valued some of his works, it had little veneration for the man and bishop, for during the controversy over the doctrines of the Alexandrian priest, Arius, Eusebius found himself on the losing side. Consequently, though a good deal has survived of Eusebius’ literary activity, it is probably only a small part of the total, which makes it very difficult to form a rounded view of him.

Three events profoundly shaped Eusebius’ life and activity. The first was his encounter with Pamphilus. Pamphilus was a great admirer of the work of Origen, though he had never known the man himself. He had studied in Alexandria under Pierius, whose devotion to Origen was such that he was known as ‘Origen Junior’ (Jerome, Vir. Ill. 76), and towards the end of the third century settled in Caesarea, where Origen had taught after his expulsion from Alexandria. There he set about restoring Origen’s heritage by making copies of all his voluminous works and continuing his labours on the text of the Scriptures.