In all these instances, the number of which might be further increased, we find homogeneousness of population at first, ethnical mixture and confusion at the end. "But what does this prove? will be asked. That too great an extension of territory is the cause of weakness? The idea is old, and out of date in our times, when steam and electricity bring the outskirts of the largest empire in closer proximity than formerly were the frontiers of the humblest sovereignty." Extension of territory does not itself prove a cause of weakness and ruin. The largest empire in the world is that of China, and, without steam or electricity, it has maintained itself for 4,000 years, and bids fair, spite of the present revolution, to last a good long while yet. But, when extension of territory is attended with the incorporation of heterogeneous masses, having different interests, different instincts, from the conqueror, then indeed the extension must be an element of weakness, and not of strength. The armies which Xerxes led into Greece were not Persians; but a small fragment of that motley congregation, the _élite_, the leaven of the whole mass, was composed of the king's countrymen. Upon this small body he placed his principal reliance, and when, at the fatal battle of Salamis, he beheld the slaughter of that valiant and noble band, though he had hundreds of thousands yet at his command, he rent his garments and fled a country which he had well-nigh conquered. Here is the difference between the armies of Cyrus and those of Xerxes and Darius. The rabbles which obeyed the latter, perhaps contained as much valor as the ranks of the enthusiastic followers of the first, though the fact of their fighting under Persian standards might be considered as a proof of their inferiority. But what interest had they in the success of the great king? To forge still firmer their own fetters? Could the name of Cyrus, the remembrance of the storming of Sardis, the siege of Babylon, the conquest of Egypt, fire them with enthusiasm? Perhaps, in some of those glorious events, their forefathers became slaves to the tyrants they now serve, tyrants whose very language they do not understand. The last armies of tottering Rome were drafted from every part of her boundless dominions, and of the men who were sent to oppose the threatening barbarians of the north, some, it might be, felt the blood of humbled Greece in their veins; some had been torn from a distant home in Egypt, or Libya; others, perhaps, remembered with pride how their ancestors had fought the Romans in the times of Juba, or Mithridates; others, again, boiled with indignation at the oppression of their Gallic brethren;--could those men respect the glorious traditions of Rome, could they be supposed to emulate the former legions of the proud city?