By the accession of Constantine to the sole sovereignty of the Roman Empire, A. D. 324, ancient Christianity may be conveniently divided into two great periods. In the first, it was a religion liable to persecution, suffering severely at times and always struggling to maintain itself; in the second, it became the religion of the State, and in its turn set about to repress and persecute the heathen religions. It was no longer without legal rights; it had the support of the secular rulers and was lavishly endowed with wealth. The conditions of the Church in these two periods are so markedly different, and the conditions had such a distinct effect upon the life and growth of the Christian religion, that the reign of Constantine is universally recognized as marking a transition from one historical period to another, although no date which shall mark that transition is universally accepted. The year 311, the year in which the Diocletian persecution ceased, has been accepted by many as the dividing point. The exact date adopted is immaterial. The principal sources in English for the history of the Christian Church before A. D. 324 are: _The Ante-Nicene Fathers. Translations of the Writings of the Fathers down to A. D. 325._ American edition, Buffalo and New York, 1885-1896; new edition, New York, 1896 (a reprint). The collection, cited as ANF, contains the bulk of the Christian literature of the period, with the exception of the less important commentaries of Origen. Eusebius, _Church History_. Translated with Prolegomena and Notes by Arthur Cushman McGiffert. In _A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church_. Second series, New York, 1890. The _Church History_ of Eusebius is the foundation of the study of the history of the Church before A. D. 324, as it contains a vast number of citations from works now lost. The edition by Professor McGiffert is the best in English, and is provided with scholarly notes, which serve as an elaborate commentary on the text. It should be in every library. This work is cited as Eusebius, _Hist. Ec._ The text used in the extracts given in this source book is that of Ed. Schwartz, in _Die Griechischen Christlicher: Schriftsteller der ersten drei Jahrhunderte_. Kleine Ausgabe, Leipsic, 1908. This text is identical with the larger and less convenient edition by the same editor. Period I. The Apostolic Age: To Circa A. D. 100 The period in the Church before the clash with Gnosticism and the rise of an apologetic literature comprises the apostolic and the post-apostolic ages. These names have become traditional. The so-called apostolic age, or to circa 100, is that in which the Apostles lived, though the best tradition makes John the only surviving Apostle for the last quarter of a century.