Moreover this unity, which we have said may be called _negative_, is necessary indeed to the understanding of the Church as Catholic, but is by no means sufficient to complete the idea of Catholicity. To it therefore must be added the _affirmative_ unity, by which Catholicism is not only divided from heretics and schismatics, but becomes in itself a coherent body with members and articulations. It is to the assertion and maintenance of this unity, which is the soul of Catholicity, and without which it cannot even be conceived, that has reference what we so often read in the monuments of antiquity about the [116]necessity of communion among the members of the Church and the [117]tokens and means of that communion. There are very distinct and innumerable testimonies about it in the ancient Fathers,[118] declaring its _necessity_, and setting forth its _mode_ of composition and coherence. For to set forth the _mode_ of this is the plain drift of what [119]Irenaeus writes in confutation of heretics by the tradition of the Apostolical churches: "For since it would be very long in the compass of our present work to enumerate the successions of all the Churches, taking that Church which is the greatest, the most ancient, and well known to all, founded and established at Rome by the two most glorious Apostles, Peter and Paul, by indicating that tradition which it has from the Apostles, and the faith which it announces to men, which has reached even to us by the succession of bishops, we confound all those, who, in whatsoever manner, either through self-pleasing, or vain glory, or blindness and evil intention, [120]gather otherwise than they ought. _For_ to this church on account of its superior chiefship, it is necessary that every Church should come[121] together, that is, the faithful who are everywhere; for in this Church the tradition which is from the Apostles has been ever preserved by those who are everywhere. ...By this ordination and succession, the tradition and preaching of the truth, which is from the Apostles in the Church, has reached down to us. And this proof is most complete, that it is one and the same vivifying faith, which has been preserved, and handed down in truth, in the Church from the Apostles to the present day." The churches, therefore, which are everywhere diffused, derive that strength and harmony of parts, out of which the whole body of the Catholic Church is made up, from the fact of their agreeing in the unity of faith and preaching with that Church of Peter, which is the greatest, the chief, and the more powerful. It follows that the Primacy of Peter, and the authority inherent in it to effect unity, is that principle which Christ selected, that the Church which He had set up might be Catholic, and bear the note of Catholicity on its brow.