While the Byzantine Empire carried over important elements from the classical world, Western and Central Europe passed under the dominion of ideas which were as foreign to those of Greece and Rome as they are to the conceptions of to-day. We have outgrown the blind contempt of the eighteenth century and the gushing enthusiasm of the Romantic Movement; but it is still a difficult task to form a just estimate of the character of the thousand years that began with Augustine and ended with Macchiavelli. It is true that our materials grow from year to year; that the criticism of original authorities as taught in the Ecole des Chartes has become something like an exact science; that thanks to Lord Bryce the Holy Roman Empire has become intelligible; that the structure and function of institutions have been patiently analysed by Waitz and Stubbs, Fustel de Coulanges and Vinogradoff, Maitland and Gierke; that literature and art, scholasticism and the Universities, have found their chroniclers and interpreters; that every ruler and every State, every treaty and every council, may be studied in monographs innumerable. But the Middle Ages were above all the reign of the Catholic Church; and we are still far from agreement as to the merits and influence of that venerable institution which, be it human or divine, occupies a unique place in the story of civilization. In the middle decades of last century the history of the mediaeval Church was related from very different standpoints in the widely-read works of Neander and Milman; but it was only with the opening of the Vatican archives by Pope Leo XIII in 1881 that it became possible to set forth the whole story of the Papacy and to understand the working of the machinery of Catholicism. So vast is the accumulation of official acts and documents, and such technical training is required for the task, that we shall have to wait many years till the material is surveyed in its entirety and its results made available for the use of the historian. Some idea of the value of the Registers may be gained from the Master of Balliol's pregnant lectures on Church and State in the Middle Ages, based on the 8,000 documents of the eleven years of the rule of Innocent IV in the middle of the thirteenth century. The study of these documents, he tells us, stirred him to admiration of the organization of the Papacy, and convinced him of its enormous superiority over its secular contemporaries as a centre not merely of religion but of law and government; but he adds that he derived an equally profound impression of the abuses which ate into the heart of the system, of the growing bitterness which it inspired, and of the devastating effects of the passion to erect a powerful principality in the heart of Italy.