III. We must be careful to distinguish between the authority of one or a certain number of the Fathers, and the consentient testimony of all of them. It is evident that the former is not infallible, because the Church’s approbation of their writings is not intended to be a guarantee of the truth of all that they teach. Some particular works, as, for instance, St. Cyril’s Anathemas, have, however, received this guarantee. The Church’s approbation implies: (1) that the writings approved were not opposed to any doctrine publicly held by the Church in the time of the author, and consequently were not subject to any censure; (2) that the doctrines for which the Father was renowned, and on which he insisted most, are positively probable; (3) that there is a strong presumption that the doubtful expressions of the Fathers should be interpreted in accordance with the commonly received doctrine, and that no discrepancy should be admitted among them except on the strongest grounds; (4) under extraordinary circumstances it may give us a moral certainty of a doctrine when, for instance, some illustrious Father has, without being contradicted by the Church, openly enforced that doctrine as being Catholic, and has treated those who deny it as heretics. When, however, all the Fathers agree, their authority attains its perfection. The consent of the Fathers has always been looked upon as of equal authority with the teaching of the whole Church, or the definitions of the Popes and Councils. But inasmuch as it is hardly possible to ascertain the opinions of every Father on every point of doctrine, and as the Holy Ghost prevents the Church from ascribing to the whole body of the Fathers any doctrine which they did not hold, it follows that the consent of the Fathers must be regarded as fully ascertained whenever those of them whose writings deal with a given doctrine agree absolutely or morally, provided that they are numerous and belong to different countries and times. The number required varies with the nature of the doctrine, which may be public, a matter of daily practice and of great importance, or, on the other hand, may be of an abstract, speculative character, and comparatively unimportant: and with
