Ecclesiastical History

Eusebius of Caesarea (Pamphilus) (c. 260–339). Eusebius was born in Palestine and received his education in the schools of Jerusalem and Antioch. He studied the works of Plato and Philo of Alexandria; the teaching of Origen influenced him especially.
The nickname “Pamphilus,” more precisely “the Pamphilians,” he received because of his friendship with a certain presbyter Pamphilus. Later, however, this nickname began to be perceived as his own second name.

During the persecution under Diocletian, he was one of the leaders of the catechetical school in Caesarea. He managed to save its library and even enrich it with new manuscripts.
When disputes began about the nature of Christ, he supported Arius—more for personal reasons than for theological ones.
At the First Ecumenical Council, he spoke up by proposing the use of the baptismal Symbol of Faith as a conciliatory formulation. This initiative was accepted, but the symbol itself was supplemented with the term “consubstantial.” Eusebius agreed with this “for the sake of church peace,” but throughout the rest of his life he leaned toward semi-Arianism, petitioning Emperor Constantine on behalf of his fellow believers.

Despite the disputable nature of his doctrinal views, Eusebius of Caesarea is rightly regarded as the father of church history. His best-known work is devoted to the history of Christianity up to the year 324, using both church and state archives. He is also associated with the famous panegyric “Life of Constantine,” as well as smaller works about the history of martyrs.

He also authored theological works: “Preparation for the Gospel,” “Proof of the Gospel’s Validity,” “Against Hierocles,” “Extracts from the Prophets Concerning Christ,” “Theophany,” “Two Books Against Marcellus,” “Three Books on Ecclesiastical Theology,” and others.