ABSTRACT
THE Roman world added but little to its area during the first half of the Empire : it diminished during the second half, and but few provinces were added, in the years separating Augustus from Marcus Aurelius, to those acquired in the course of the last two centuries of the Republic. For, on the one hand, the territory of the Caesars was practically identical with the boundaries of the portion of the world known to the ancients and, on the other, Augustus, in a testament which was a model of wisdom and was for the most part respected by his successors, had counselled prudence and moderation. At a time when communications were slow and uncertain the administration of a vast body of nations entailed innumerable difficulties, the extent of which was perceived by the first emperors though they weighed far more heavily upon Aurelian, Diocletian and Theodosius at a time when the whole front was attacked by tribes in arms. The construction of Constantinople was in itself a reply to the ever-increasing anxieties which were inseparable from the defence of a frontier thousands of miles long.
