For the period before the outbreak of the great christological controversies, the ecclesiastical historians are of great value. There are no less than four continuations of the _Ecclesiastical History_ of Eusebius accessible: the ecclesiastical histories of Socrates, 324-439 (ed. R. Hussey, Oxford, 1853); of Sozomen, 324-425 (ed. R. Hussey, Oxford, 1860); of Rufinus, 324-395, which is appended to a Latin version or rather revised and “edited” Latin version of Eusebius; of Theodoret, 323-428 (ed. Gaisford, Oxford, 1854). Fragments of the _Ecclesiastical History_ of the Arian Philostorgius, from the appearance of Arius as a teacher until 423, have been translated and are to be found in Bohn’s _Ecclesiastical Library_. For the period after the Council of Ephesus, A. D. 431, there is no such abundance, but Evagrius, of whose history (ed. Parmentier and Bidez, London, 1898) there is a translation in Bohn’s _Ecclesiastical Library_, though not in PNF, is of great value as he gives many original documents; and a portion of the _Ecclesiastical History_ of John of Ephesus (trans. by R. P. Smith, Oxford, 1860) carries the history to about 600. There are also works devoted to the history of the West by Gregory of Tours, the Venerable Bede, and Paulus Diaconus, and others of the greatest value for the third period of this division. They will be mentioned in their place. As the series of the great church councils begins with the Christian Empire, the _History of the Councils_, by Hefele, becomes indispensable to the student of ecclesiastical history, not only for its narrative but for the sources epitomized or given in full. It has been translated into English as far as the close of the eighth century, or well into the beginnings of the history of the mediæval Church. The new French translation should be used if possible as it contains valuable additional notes. In connection with Hefele may be used: Percival, _The Seven Ecumenical Councils_, in PNF, ser. II, vol. XIV. Wm. Bright, _Notes on the Canons of the First Four General __ Councils_, 1882, should be consulted for this period. Bruns, _op. cit._, and Lauchert, _op. cit._, give texts only. The two great collections of secular laws are: _Codex Theodosianus_, ed. Mommsen and Meyer, Berlin, 1905. _Corpus Juris Civilis_, ed. Krüger, Mommsen, Schoell, and Knoll, Berlin, 1899-1902. _The Cambridge Medieval History_, vol. I, 1912, covers the period beginning with Constantine and extending to the beginning of the fifth century. It contains valuable bibliographies of a more discriminating character than those in the _Cambridge Modern History_, and render bibliographical references unnecessary. To this the student is accordingly referred for such matters. The second volume of this work will cover the period 500-850. Period I: The Imperial State Church Of The Undivided Empire, Or Until The Death Of Theodosius The Great, 395