Eusebius wrote his Ecclesiastical History about the year 324. He was the first person to try to summarize the history of Christianity up through his own day. Eusebius was the bishop of Caesarea Maritima in Palestine, and he wrote this work to help his readers understand the significance and history of the spread of Christianity from the time of Jesus and the apostles to his own day, about three centuries later. To write his Ecclesiastical History, Eusebius made use of copious sources that were at his disposal. He was fortunate to have a rich library at Caesarea. The library there had been established by the great church father Origen of Alexandria, who spent a lot of time teaching in Caesarea. Eusebius also had access to the library records in Jerusalem. Eusebius’s Ecclesiastical History is significant because it presents, from a uniquely Christian perspective, the history of Christianity’s first centuries and preserves many sources, such as those from the early bishop Papias, whose important works would otherwise remain lost to us today.