Evidently the original error of the Romans was the undue
extension of their power. This was recognised by no less a statesman than
Augustus, the founder of the Empire; but even in his time it was too late to
sound a retreat; he could only register a protest against further annexations.
Embracing the whole of the Mediterranean littoral and a large part of the
territories to the south, east, and north, the Empire was encumbered with three
land frontiers of enormous length. Two of these, the European and the Asiatic,
were perpetual sources of anxiety, and called for separate military
establishments. That neither might be neglected in the interest of the other it
was reasonable to put the imperial power in commission between two colleagues.
Diocletian (284-305 A.D.) was the first to adopt this plan; from his time
projects of partition were in the air and would have been more regularly
carried out, had not experience shown that partitions led naturally to civil
wars between rival Emperors. In 395, on the death of the great Theodosius, the hazardous
expedient was given a last trial. His youthful sons, Arcadius and Honorius,
were allowed to divide the Empire; but the line of partition was drawn with
more regard to racial jealousies than military considerations. It extended from
the middle Danube (near Belgrade) to a point near Durazzo on the Adriatic
coast, and thence to the Gulf of Sidra. East of this line lay the sphere of
Greek civilisation, the provinces which looked to Alexandria and Antioch and
Constantinople as their natural capitals. West of it the prevailing language
was Latin, and the higher classes of society modelled themselves upon the
Italian aristocracy.
