The earliest writer of church history properly so called is Eusebius, Bishop of Cæsarea, † 340. During the fifth century certain members of the Greek Church continued his work. The Western Church did not so soon engage upon undertakings of that sort, and was contented with translations and reproductions of the materials that had come down from the Greeks instead of entering upon original investigations. During the middle ages, in consequence of the close connection subsisting between Church and State, the Greek _Scriptores historiæ Byzantinæ_, as well as the Latin national histories, biographies, annals, and chronicles, are of the very utmost importance as sources of information regarding the church history of their times. It was the Reformation, however, that first awakened and inspired the spirit of true critical research and scientific treatment of church history, for the appeal of the Reformers to the pure practices and institutions of the early days of the church demanded an authoritative historical exposition of the founding of the church, and this obliged the Catholic church to engage upon the studies necessary for this end. The Lutheran as well as the Catholic Church, however, down to the middle of the 17th century, were satisfied with the voluminous productions of the two great pioneers in Church history, Flacius and Baronius. Afterwards, however, emulation in the study of church history was excited, which was undoubtedly, during the 17th century, most successfully prosecuted in the Catholic Church. In consequence of the greater freedom which prevailed in the Gallican Church, these studies flourished conspicuously in France, and were pursued with exceptional success by the Oratorians and the Order of St. Maur. The Reformed theologians, especially in France and the Netherlands, did not remain far behind them in the contest. Throughout the 18th century, again, the performances of the Lutheran Church came to the front, while a laudable rivalry leads the Reformed to emulate their excellencies. In the case of the Catholics, on the other hand, that zeal and capacity which, during the 17th century, had won new laurels in the field of honour, were now sadly crippled. But as rationalism spread in the domain of doctrine, pragmatism spread in the domain of church history, which set for itself as the highest ideal of historical writing the art of deducing everything in history, even what is highest and most profound in it, from the co-operation of fortune and passion, arbitrariness and calculation. It was only in the 19th century, when a return was made to the careful investigation of original authorities, and it came to be regarded as the task of the historian, to give a conception and exposition of the science as objective as possible, that this erroneous tendency was arrested.