In the third period are to be placed the beginnings of the Middle Ages, as the German invaders had long before 500 established their kingdoms and had begun to dominate the affairs of the West. But the connection of the Church of the West, or rather of Italy, with the East was long so close that the condition of the Church is more that of a dissolution of the ancient imperial State Church than of a building up of the mediæval Church. At the same time, the transition to the Middle Ages, so far as the Church is concerned at least, takes place under the influence of the ancient tradition, and institutions are established in which the leading elements, taken from ancient life, are not yet transformed by Germanic ideas. The East knew no Middle Age. For a history of the Eastern Church other divisions would have to be made, but in a history in which, for practical reasons, the development is traced in Western Christianity, the affairs of the Eastern Church must be treated as subordinate to those of Western Christianity. For the second division of the history of ancient Christianity, the principal sources available in English are the translations in _A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church_. Edited by Ph. Schaff and H. Wace. The _First Series_ of this collection (PNF, ser. I) contains the principal works of Augustine and Chrysostom. The _Second Series_ (PNF, ser. II) is for historical study even more valuable, and gives, generally with very able introductions and excellent bibliographies, the most important works of many of the leading patristic writers, including the principal ecclesiastical historians, as well as Athanasius, Gregory of Nazianzus, Gregory of Nyssa, Basil the Great, Cyril of Jerusalem, Hilary of Poitiers, Jerome, Rufinus, Cassian, Vincent of Lérins, Leo the Great, Gregory the Great, and others. These translations are in part fresh versions, and in part older versions but slightly, if at all, revised, taken from the _Library of the Fathers of the Holy Catholic Church anterior to the Division of the East and West_, Oxford, 1838, _et seq._