Insofar as persecution was legalized, it is to be understood not as a putting down of a new religious belief, but as an attack on its political and social side. In the case, for instance, of Cyprian, bishop of Carthage, who after a flight and a banishment was put to death under Valerian and Gallienus (258), the bishop's far-reaching activities are the presumptive reason for his fate. It is to be remembered, as Gibbon notes, that in ten years of Cyprian's tenure of office four emperors themselves died by the sword, with their families and their adherents. At times, no doubt, the attack on Christians was unprovoked, consisting as it might in a challenge to a Christian to swear allegiance by or sacrifice to the statue of the emperor, when he was willing to swear by his own creed. The public worship of the emperor was the one semblance of a centralized religious organization which, like that of the Christian Church, existed throughout the empire. Precedented by old Egyptian and eastern usage, and by the practice of Alexander and his successors, it had first appeared in Rome in the offer of the cringing senate to deify Julius Cæsar, and in the systematic measures of Augustus to have Julius worshipped as a God (divus), an honour promptly accorded to himself in turn. The apotheosis was signalized by giving the names of Julius and Augustus to the months Quintilis and Sextilis; and only the final unpopularity of Tiberius prevented the substitution of his name in turn for that of September, an honour offered to and refused by him in his earlier life.