Arthur Middleton concludes on the bishop as the focus of unity

The Church is one with a visible external unity. The essence of that unity lies in a spiritual fact – the life of Christ which is communicated to the Church: but this life is communicated to a visible society, bound together by visible bonds of external association!

To this visible society he that would be Christ’s must belong: ‘he cannot have God for his father who has not the Church for his mother’ [De Unitate 6]; schism separates from Christ in such completeness that not even martyrdom can expiate it [ibid, De Unit. Eccles. 14].

Of this unity the bishop is in each community at once the symbol, the guardian [ibid, De Unit. Eccles. 5], and the instrument. He is the instrument of it because ‘the bishops, who succeed to the Apostles by an ordination which makes them their representatives,’ are the possessors of that sacerdotal authority and grace with which Christ endowed his Church, and which is necessary for her existence [ibid, Ep. 68.8].

This plenitude of the priesthood is in every bishop, and in every bishop equally, just as every one of the Apostles was ‘endowed with an equal fellowship of honour and power.’ But the apostolate, which was finally given to all equally, was given first to St Peter, that by its being given first to one man, there might be emphasized for ever the unity which Christ willed to exist among the distinct branches or portions of his Church [ibid, De Unit. Eccles. 4]. The episcopate which belongs to each bishop belongs to him as one of a great brotherhood linked by manifold ties into a corporate unity [ibid, Ep. 51.24].

A bishop stands, then, in various relations to the Church. In virtue of his election he represents his flock [ibid, Ep. 68.8]: he is a part of the church and in a sense responsible to it and stands in a certain constitutional, though not clearly defined, relation to his presbyterate and the clergy generally. They are his recognized council, advisers and co-operators; he does nothing without consulting them [ibid, Ep. 5.4].

But over and above this he represents divine authority. He is divinely appointed; he has not taken this honour upon himself [ibid, Ep. 69.3]. Moreover, in the exercise of his authority, he is responsible to no man outside his church but to God only, though the provincial council has a certain authority over the individual bishop [ibid, Ep. 64.1].

Nevertheless, the independence of each bishop is asserted by Cyprian with unrestricted completeness [ibid, Ep. 71.3]. His respect for the see of Rome, as being in a special historical sense what every episcopate is essentially, as possessing the same authority – the see of Peter will not go to the length of allowing it any jurisdiction over other churches. It may be in a special way the symbol of unity, as Peter was among the Apostles, but it is nothing more [ibid, Epp. 51.8; 54.14].