+2.+ We shall best show how marvellous and vast our subject is by comparing the most famous Empires which preceded, and which have been the favourite themes of historians, and measuring them with the superior greatness of Rome. There are but three that deserve even to be so compared and measured: and they are these. The Persians for a certain length of time were possessed of a great empire and dominion. But every time they ventured beyond the limits of Asia, they found not only their empire, but their own existence also in danger. The Lacedaemonians, after contending for supremacy in Greece for many generations, when they did get it, held it without dispute for barely twelve years. The Macedonians obtained dominion in Europe from the lands bordering on the Adriatic to the Danube,—which after all is but a small fraction of this continent,—and, by the destruction of the Persian Empire, they afterwards added to that the dominion of Asia. And yet, though they had the credit of having made themselves masters of a larger number of countries and states than any people had ever done, they still left the greater half of the inhabited world in the hands of others. They never so much as thought of attempting Sicily, Sardinia, or Libya: and as to Europe, to speak the plain truth, they never even knew of the most warlike tribes of the West. The Roman conquest, on the other hand, was not partial. Nearly the whole inhabited world was reduced by them to obedience: and they left behind them an empire not to be paralleled in the past or rivalled in the future. Students will gain from my narrative a clearer view of the whole story, and of the numerous and important advantages which such exact record of events offers. [Sidenote: B.C. 220-217. The History starts from the 140th Olympiad, when the tendency towards unity first shows itself.]