In his instructions for the education of his successor, Frederick prescribed a thorough course of European history from the time of the Emperor Charles V. (1519–1556) to his own reign. This had been the favourite study of his own youth, so that at his accession he realised to the full that modern Europe owed little of its political contour to chance, but much to the aspirations and struggles of the several states during the last two centuries. For modern Europe was no older than Charles V. Right through the Middle Ages the Christian world maintained that supreme authority, like truth, ought to be one, and that every Christian should look up to the Emperor in matters temporal as he looked up to the Pope in matters spiritual. On the secular side, however, this theory had crumbled beneath its own weight. Even a Charlemagne could not really rule the world. As the various races of mankind who lived in England, France, Spain, and Scandinavia gradually came under the sway of a few national rulers, the Emperor dwindled into a dignified president of German princes. His lordship of the world survived only in distracting claims to rule more widely and more exclusively than his attenuated power could warrant. Two sharp shocks heralded modern times. First Columbus bestowed upon his masters, the Kings of Spain, a new world which had never heard of Pope and Emperor and which the Emperor at least did not pretend to sway. Then Luther, wrestling blindly with the papacy, shattered the central pillar of the mediæval world, and modern history, the biography of a group of independent states, began. These states, however, did not enjoy unchallenged independence. Each had to work out its own religious settlement, and—if it embraced the Reformation—had to repel, with whatever help it could find, the rescue-work of the Pope and his allies. To the end of the sixteenth century, through the careers of Charles V., Elizabeth, William of Orange, Henry of Navarre, Romanist and Protestant States always tended to fall apart into two hostile camps. Even in Frederick’s time religious affinity always counted for something. He had laid history to heart and, as we shall see, profited in his dealings with England by the old cry of “Church in danger.” On his lips the cry was a mere ruse. The day of crusades was over. In the sixteenth century Spain, Austria, and Italy rejected the Reformation; England established its own Church; France came to terms with the Huguenots. At the great Peace of Westphalia Germany established parity between the warring creeds, a boon tardily won by thirty years of desolation. Thenceforward affairs of state came first in every land. Louis XIV.’s revocation of the Edict of Nantes in 1685 proved that religious aggression was to be feared only as the sequel of undue political preponderance. From the birth of modern states down to our own time, the bugbear of the nations has been world-rule and their watchword equilibrium.