The _material_ part, amplitude and extension.--The _formal_ part, not only negative, but affirmative.--_Negative_, as expelling from the one true Church all heretics and schismatics: testimonies to it 237 _Affirmative_, at making a coherent body with members and articulations 238 Testimonies to the _mode_ of this coherence, in Irenaeus, Cyprian, and Tertullian, and the other Fathers, summed up in S. Leo 239 Hence answers to the question whether the doctrine of S. Peter's Primacy is contained in the creed.--It is involved in one Catholic Church 243 CHAPTER IX. THE NATURE, MULTIPLICITY, AND FORCE OF PROOF FOR S. PETER'S PRIMACY. Different sorts of proof.--1. The principal here used, and the subsidiary.--Their joint force 246 Hence, I. The nature of the answer required to it.--2. The proof, if unanswered, demonstrates the Primacy to be revealed 247 3. Enquiry into the _certitude_ of the proof used 248 I. Force of the proof _in itself_ and _absolutely_.--Two conditions requisite, and here found, authenticity of the documents, and clearness of their evidence.--Number and harmony of scriptural testimonies to the Primacy 249 The parallel of Julius Caesar 250 Collateral proof, supporting that of the holy Scriptures, so that the whole consists in the harmony of these four:--1. Scriptural documents.--2. Ancient witnesses.--3. Analogy.--4. Facts of Christian history, in fourteen distinct classes 251 Prodigious force of this compound proof 256 No counter religious system producible by Greek, Anglican, or pure Protestant, but mere negation and objection 257 II. Force of the proof _comparatively_ with other doctrines: comparison with the texts on which Anglicans, Lutherans, and Calvinists severally rely 259 Retort that all but Catholics are opposed to our interpretation; answer, that from Catholics alone we are to gather the truth 260 Yet all protestants not agreed in opposing our interpretation and reasons why their opposition is of little moment 261 Compare, likewise, opposition to the Church in the fourth, fifth, and sixth centuries 264 And again the conduct of Lutherans and Anglicans in maintaining their own distinctive texts.--But what, then, are the true criteria of documentary evidence? They are four:--