Eusebius (260 - 339 AD) was an early Christian scholar and priest in the church at Caesarea. His mentor Pamphilius was an ardent disciple of Origen and Eusebius became deeply influenced by the Origenist tradition. His major work was his History of the Church, a massive piece of research that preserves quotations from many older writers that would otherwise have been lost.
It covers the foundation of the Christian church from the time of Christ through the end of Eusbius' own life during the reign of Constantine. Despite the value of his work most scholars agree that his literary work is subpar.
History of the Church