Again, who can estimate the debt which civilization, in its largest and most comprehensive sense, owes to the fathers of the early church, in the elaboration of Christian doctrine. They found the heathen world enslaved by a certain class of most degrading notions of God, of deity, of goodness, of the future, of rewards and punishments. Indeed, its opinions were wrong and demoralizing in almost every point pertaining to the spiritual relations of man. They met the wants of their times by seizing on the great radical principles of Christianity, which most directly opposed these demoralizing ideas, and by giving them the prominence which was needed. Moreover, in the church itself, opinions were from time to time broached, so intimately allied with pagan philosophies and oriental theogonies, that the faith of Christians was in danger of being subverted. The Scriptures were indeed recognized to contain all that is essential in Christian truth to know; but they still allowed great latitude of belief, and contradictory creeds were drawn from the same great authority. If the Bible was to be the salvation of man, or the great thesaurus of religious truth, it was necessary to systematize and generalize its great doctrines, both to oppose dangerous heathen customs and heretical opinions in the church itself. And more even than this, to set forth a standard of faith for all the ages which were to come; not an arbitrary system of dogmas, but those which the Scriptures most directly and emphatically recognized. Christian life had been set forth by the martyrs in the various forms of teaching, in the worship of God, in the exercise of those virtues and graces which Christ had enjoined, in benevolence, in charity, in faith, in prayer, in patience, in the different relations of social life, in the sacraments, in the fasts and festivals, in the occupations which might be profitably and honorably carried on. But Christianity influenced thought and knowledge as well as external relations. It did not declare a rigid system of doctrines when first promulgated. This was to be developed when the necessity required it. For two centuries there were but few creeds, and these very simple and comprehensive. Speculation had not then entered the ranks, nor the pagan spirit of philosophy. There was great unity of belief, and this centered around Christ as the Redeemer and Saviour of the world. But, in process of time, Christianity was forced to contend with Judaism, with Orientalism, and with Greek speculation, as these entered into the church itself, and were more or less embraced by its members. With downright Paganism there was a constant battle; but in this battle all ranks of Christians were united together. They were not distracted by any controversies whether idolatry should be or should not be tolerated. But when Gnostic principles were embraced by good men, those which, for instance, entered into monastic or ascetic life, it was necessary that some great genius should arise and expose their oriental origin, and lay down the Christian law definitely on that point. So when Manichaeism, and Arianism, and other heretical opinions, were defended and embraced by the Christians themselves, the fathers who took the side of orthodoxy in the great controversies which arose, rendered important services to all subsequent generations, since never, probably, were those subtle questions pertaining to the Trinity, and the human nature of Christ, and predestination, and other kindred topics, discussed with so much acumen and breadth. They occupied the thoughts of the whole age, and emperors entered into the debates on theological questions with an interest exceeding that of the worldly matters which claimed their peculiar attention. It is not easy for Christians of this age, when all the great doctrines of faith are settled, to appreciate the prodigious excitement which their discussion called forth in the times of Athanasius and Augustine. The whole intellect of the age was devoted to theological inquiries. Everybody talked about them, and they were the common theme on all public occasions. If discussions of subjects which once had such universal fascination can never return again, if they are passed like Olympic games, or the discussions of Athenian schools of philosophy, or the sports of the Colosseum, or the oracles of Dodona, or the bulls of mediaeval popes, or the contests of the tournament, or the "field of the cloth of gold," they still have a historical charm, and point to the great stepping-stones of human progress. If they are really grand and important ideas, which they claimed to be, they will continue to move the most distant generations. If they are merely dialectical deductions, they are among the profoundest efforts of reason in the Christian schools of philosophy.