Reorganization.
The fourth century saw the great reforms under Diocletian and Constantine. The empire was reorganized and, for the time being, strengthened. But the new vigor was vicious in type. It was oriental despotism thinly disguised, as shown by the strange new garb of the emperors, no longer great generals and first citizens; and by the horde of office-holders with novel, high-sounding titles fitted to the various grades of the new bureaucracy.
A line of cleavage was developed by the establishment of the double capital and the joint emperors. East and West began to separate. The division was in part dictated by the difficulty of administering the vast empire from one center in a period when communication was incredibly slow as compared with our modern facilities of steam and electricity. And in this division was a double seed. From one kernel was to spring disaster for Italy and the West. From the other was to germinate the Eastern Empire, destined to be the fortunate and stupid conservator of culture and learning throughout the dark ages.