Strong and masterful Popes had for centuries insisted on exercising powers which, they asserted, belonged to them as the successors of St. Peter and the representatives of Christ upon earth. Ecclesiastical jurists had translated their assertions into legal language, and had expressed them in principles borrowed from the old imperial law. Precedents, needed by the legal mind to unite the past with the present, had been found in a series of imaginary papal judgments extending over past centuries. The forged decretals of the pseudo-Isidor (used by Pope Nicholas I. in his letter of 866 A.D. to the bishops of Gaul), of the group of canonists who supported the pretensions of Pope Gregory VII. (1073-1085),—Anselm of Lucca, Deusdedit, Cardinal Bonzio, and Gregory of Pavia,—gave to the papal claims the semblance of the sanction of antiquity. The Decretum of Gratian, issued in 1150 from Bologna, then the most famous Law School in Europe, incorporated all these earlier forgeries and added new ones. It displaced the older collections of Canon Law and became the starting-point for succeeding canonists. Its mosaic of facts and falsehoods formed the basis for the theories of the imperial powers and of the universal jurisdiction of the Bishops of Rome.(3) The picturesque religious background of this conception of the Church of Christ as a great temporal empire had been furnished by St. Augustine, although probably he would have been the first to protest against the use made of his vision of the City of God. His unfinished masterpiece, _De Civitate Dei_, in which with a devout and glowing imagination he had contrasted the _Civitas Terrena_, or the secular State founded on conquest and maintained by fraud and violence, with the Kingdom of God, which he identified with the visible ecclesiastical society, had filled the imagination of all Christians in the days immediately preceding the dissolution of the Roman Empire of the West, and had contributed in a remarkable degree to the final overthrow of the last remains of a cultured paganism. It became the sketch outline which the jurists of the Roman Curia gradually filled in with details by their strictly defined and legally expressed claim of the Roman Pontiff to a universal jurisdiction. Its living but poetically indefinite ideas were transformed into clearly defined legal principles found ready-made in the all-embracing jurisprudence of the ancient empire, and were analysed and exhibited in definite claims to rule and to judge in every department of human activity. When poetic thoughts, which from their very nature stretch forward towards and melt in the infinite, are imprisoned within legal formulas and are changed into principles of practical jurisprudence, they lose all their distinctive character, and the creation which embodies them becomes very different from what it was meant to be. The mischievous activity of the Roman canonists actually transformed the _Civitas Dei_ of the glorious vision of St.