But to realise all the circumstances under which Constantinople was founded, we should remember yet another fact. The rule of the Roman world by one man had broken down, just as the rule of that world by the citizens of Rome had failed. A single arm, it was discovered, could not defend the frontiers of that vast realm against the numerous and fierce foes who threatened its existence; or repress the insurrections which ambitious men readily raised in widely scattered provinces, when the central authority was too distant to strike promptly and with the necessary vigour. Hence the famous scheme of Diocletian to divide the burden of defending and administering the Empire between four rulers, bound to one another by community of interest. As originally devised, it was a short-lived scheme. But it was superseded only so far as its details were concerned; its fundamental idea had come to stay. At first sight, indeed, the restoration of the system of single rule, in the person of Constantine, seemed to imply the abandonment of the multiple form of government which Diocletian had established. Possibly Constantine may have entertained such a purpose for some time. But eventually he adhered to Diocletian’s plan, and thought to improve upon it by the introduction of the dynastic and hereditary factor, hoping that by distributing the government among members of the same family, joint rule would prove more cordial and permanent, because resting upon a more solid basis. Accordingly, he arranged that after his death the government should be divided between his three sons and two nephews. [Illustration: GALATA FROM THE AQUEDUCT OF VALENS The Galata Tower, which is such a prominent feature from this standpoint, is used as a station for signalling any outbreak of fire, and also the quarter of the city in which it occurs.] This was an excessive partition of power, and proved unsatisfactory. But the view that the welfare of the State required the attention and abilities of more than one ruler was consistently upheld, so long as Western and Eastern Europe formed integral parts of the same dominion.