10. The idea of one Catholic Church seems to have resulted from the intense struggle against the various forms of heresy, which had divided the early Christians into sects somewhat like the various Protestant denominations of to-day. This conception of ecclesiastical unity and universality had two sides: doctrine and ceremony. To teach the true doctrine and to perpetuate sacramental unity the priesthood was created. The persecutions emphasised the fundamental doctrines which united all Christians and made them conscious of this unity of belief. In order to enforce this uniformity the Bishop of Rome exercised the power of excommunication. Victor took it upon himself to excommunicate the Bishop of Ephesus and his fellow-officials for refusing to conform to the mode of celebrating Easter in the West (190). Irenæus emphasised the necessity and value of a spiritual unity in the Church,[157:1] and to "the very great, the very ancient, and universally known Church" of Rome he conceded the most accurate apostolic tradition.[157:2] He declared that it was "a matter of necessity that every church should agree with this Church, on account of its pre-eminent authority."[157:3] Tertullian spoke of the Catholic Church as if its eternal unity were a common concept.[157:4] It was left to Cyprian, however, to boldly hold up the occupant of the See of Rome as the representative of both the organised and the sacramental unity of the Church beyond which there could be no salvation. In his book on the _Unity of the Church_, Cyprian asked: He that abideth not in the unity of the church, doth he believe that he holdeth to the faith? He that struggleth against and resisteth this church, he that deserteth the Chair of St. Peter, upon which the church is founded, can he have any assurance that he is in the church? . . . Likewise . . . Paul teacheth the sacrament of unity saying: "There is one body and one spirit and one hope of our calling; one Lord, one faith, one baptism, one God." . . . The episcopate is indeed one . . . the church also is one . . . there is also but one head and one source. . . . Whoever is excluded from the church . . . is severed from the promises of the church. . . . He is a stranger, an outcast, and enemy. He cannot have God for his father, who hath not the church for his mother. . . . He that doth not hold this unity doth not hold the law of God . . . he partaketh not of life or of salvation.[158:1] The power of excommunication to preserve the doctrinal unity and purity of the Church implied some share in appointment and administration. From the very beginning, no doubt, the Bishop of Rome had ordained all provincial bishops, and few matters of great importance had been transacted without his consent or approval.[158:2]