The only surviving account of the Church during its crucial first 300 years. Bishop Eusebius (c. AD260-339), a learned scholar who lived most of his life in Caesarea in Palestine, broke new ground in writing The History of the Church and provided a model for all later ecclesiastical historians. In tracing the history of the Church from the time of Christ to the Great Persecution at the beginning of the fourth century and ending with the conversion the Emperor Constantine, he tried to show the.purity and continuity of the doctrinal tradition of Christianity in its struggle against persecutors and heretics, and supported his account by extensive quotations from original sources to a degree hitherto unknown.