It was by pursuing this line of argument that the early Fathers demonstrated the Apostolicity of the Catholic Church, and refuted the pretensions of contemporary sectaries. St. Irenæus, Tertullian and St. Augustine give catalogues of the Bishops of Rome who flourished up to their respective times, with whom it was their happiness to be in communion, and then they challenged their opponents to trace their lineage to the Apostolic See. "Let them," says Tertullian, in the second century, "produce the origin of their church. Let them exhibit the succession of their Bishops, so that the first of them may appear to have been ordained by an _Apostle, or by an apostolic man who was in communion with the Apostles_."(99)
And if the Fathers of the fifth century considered it a powerful argument in their favor that they could refer to an uninterrupted line of fifty Bishops who occupied the See of Rome, how much stronger is the argument to us who can now exhibit five times that number of Roman Pontiffs who have sat in the chair of Peter! I would affectionately repeat to my separated brethren what Augustine said to the Donatists of his time: "Come to us, brethren if you wish to be engrafted in the vine. We are afflicted in beholding you lying cut off from it. Count over the Bishops from the very See of St. Peter, and mark, in this list of Fathers, how one succeeded the other. This is the rock against which the proud gates of hell do not prevail."(100)
Perpetuity, or duration till the end of time, is one of the most striking marks of the Church. By perpetuity is not meant merely that Christianity in one form or another was always to exist, but that the Church was to remain forever in its _integrity_, clothed with _all_ those attributes which God gave it in the beginning. For, if the Church lost any of her essential characteristics, such as her unity and sanctity, which our Lord imparted to her at the commencement of her existence, she could not be said to be perpetual because she would not be the same Institution.
The unceasing duration of the Church of Christ is frequently foretold in Sacred Scripture. The Angel Gabriel announces to Mary that Christ "shall reign over the house of Jacob _forever_, and of his kingdom _there shall be no end_."(101) Our Savior said to Peter: "Thou art Peter, and upon this rock I will build My Church, and the gates of hell shall not prevail against it."(102) Our blessed Lord clearly intimates here that the Church is destined to be assailed always, but to be overcome, never.