We naturally glance, in the first place, to the extent of that vast empire which has had no parallel in ancient or modern times, and which was erected on the ruins of all the powerful states of antiquity. It was a most wonderful centralization of power, spreading its arms of hopeless despotism from the Pillars of Hercules to the Caspian Sea; from the Rhine and the Danube to the Euphrates and Tigris; from the forests of Sarmatia to the deserts of Africa. The empire extended three thousand miles from east to west, and two thousand from north to south. It stretched over thirty-five degrees of latitude, and sixty-five of longitude, and embraced within its limits nearly all the seas, lakes, and gulfs which commerce explored. It contained 1,600,000 square miles, for the most part cultivated, and populated by peoples in various stages of civilization, some of whom were famous for arts and wealth, and could boast of heroes and cities,--of a past history brilliant and impressive. In nearly the centre of this great empire was Mediterranean Sea, which was only, as it were, an inland lake, upon whose shores the great cities of antiquity had flourished, and towards which the tide of Assyrian and Persian conquests had rolled and then retreated forever. The great rivers--the Nile, the Po, and the Danube--flowed into this basin and its connecting seas, wafting the produce of distant provinces to the great central city on the Tiber. The boundaries of the empire were great oceans, deserts, and mountains, beyond which it was difficult to extend or to retain conquests. On the west was the Atlantic Ocean, unknown and unexplored--that mysterious expanse of waters which filled navigators with awe and dread, and which was not destined to be crossed until the stars should cease to be the only guide. On the northwest was the undefined region of Scandinavia, into which the Roman arms never penetrated, peopled by those barbarians who were to be the future conquerors of Rome, and the creators of a new and more glorious civilization,--those Germanic tribes which, under different names, had substantially the same manners, customs, and language,--a race more unconquerable and heroic than the Romans themselves, the future lords of mediaeval Europe, the ancestors of the English, the French, the Spaniards, and the Germans. On the northwest were the Sarmatians and Scythians--Sclavonic tribes, able to conquer, but not to reconstruct; savages repulsive and hideous even to the Goths themselves. On the east lay the Parthian empire, separated from Roman territories by the Euphrates, the Tigris, and the Armenian mountains. The Caucasian range between the Euxine and the Caspian seas presented an insuperable barrier, as did the deserts of Arabia to the Roman legions. The Atlas, the African desert, and the cataracts of the Nile formed the southern boundaries. The vulnerable part of the empire lay between the Danube and Rhine, from which issued, in successive waves, the Germanic foes of