Thus it is that the inherent notion of the Church, as one visible body, and the whole dispensation by which visible things answer to invisible, as their archetypes, demand one visible head. Now to this _inherent_ necessity let us add the force of _positive_ teaching. When our Lord in almost His last words to His Church prays to His Father, "while I was with them in the world, I kept them in Thy name--but now I come to Thee," what does He but suggest the appointment of another visible head to take that place which He was leaving? and further, what does He but name one to that high dignity, when He calls him "the greater" and "the ruler" among his brethren, commits them to him to be confirmed by him, and makes him the shepherd of the whole flock? What else had He done but prepare them for such a nomination, when He promised _one_ that he should be the foundation of His Church, and the bearer of the keys? What else did Christians from the beginning see in such an one, when they called him the _head_, the _centre_, the _fountain_, the _root_, the _principle_ of ecclesiastical unity? Let us remark, once more, as a confirmation of the above, that the archetype of visible unity in the Church, which our Lord sets before us in His prayer to the Father, is no other than that most high and solemn of all things conceivable, the mutual indwelling of the Father and the Son. "Holy Father, keep them in Thy name whom Thou hast given Me, that they may be one, as We also are;" and again, for all successive generations of the faithful, "that they all may be one, as Thou, Father, art in Me, and I in Thee, that they also may be one in Us, that the world may believe that Thou hast sent Me." Now the relation established by our Lord between Peter and the rest of the Apostles, by appointing him the visible head of the Church, and between Peter's successor and all bishops, does represent, so far as earthly things may, and in a degree which nothing else on earth reaches to, the mutual relation of the three divine Persons to each other. For as these are distinct, but inseparable, so, too, are the Apostles. As the fulness of the Godhead is _first_ in the Father and _then_ in the Son and in the Holy Spirit, so the fulness of power _first_ promised and given to Peter, is _then_ propagated to the other Apostles united with him. As in the Father the economy of the divine Persons is summed up under one head, and gathered into a monarchy, so in Peter is gathered up the fulness of ecclesiastical power, which, through union with him, is one in all, as the Church is one, and the Episcopate one. Moreover, as it is the dignity of the Father to be the exemplar, principle, root, and fountain of unity in the Trinity, so is it the dignity of Peter to be the exemplar, principle, root, and fountain of visible unity in the kingdom of God, which is the Church. This is alluded to by Pope Symmachus, thirteen hundred and fifty years ago: "There is one