In practice the procedure consists in extending to the universal church the use of the Office and Mass of a saint in which the title of doctor is applied to him. The decree is issued by the Congregation of Sacred Rites and approved by the pope, after a careful examination, if necessary, of the saint's writings. It is not in any way an ex cathedra decision, nor does it even amount to a declaration that no error is to be found in the teaching of the Doctor. It is, indeed, well known that the very greatest of them are not wholly immune from error.

SECT. 26.— The Writings of the Fathers.

I. The “Fathers” are those representatives of Tradition who have been recognized by the Church as excelling in sanctity and in natural and supernatural gifts, and who belong to the early Church. This latter mark distinguishes them from the doctors who have lived more recent times, but it has only a secondary influence upon their authority. No great significance was attached by the Council of Ephesus or the older theologians to the antiquity of the Fathers. The Church herself has bestowed the title of “Doctor Ecclesiae,” by which it honours the most illustrious Fathers in the Liturgy, upon many saints of later date, and has thereby put them on the same level. We may even say that the canonization of a theological writer raises him to some extent to the dignity a “Father.” Still, the mark of antiquity is not without importance, as we have already explained.

II. The domain of doctrine covered by the authority and infallibility of the Fathers is co-extensive with that of the Church, whose mouthpiece they are. Hence it does not embrace truths of a purely natural and philosophical character, or truths revealed only per accidens, because these are not part of the public teaching of the Church. On the other hand, their authority is not limited to their testimony to truths expressly and formally revealed, but extends to the dogmatico-theological interpretation of the whole Deposit of Revelation. The material and formal authority of the Fathers — that is, the subject-matter with which they deal, and the ecclesiastical use of their writings — are beautifully expressed by St. Vincent of Lerins, when speaking of the Fathers quoted at the Council of Ephesus: “Only these ten, the sacred number of the commandments, were brought forward at Ephesus as teachers, counsellors, witnesses, and judges; [and the Council] holding their doctrine, following their advice, believing their testimony, and obeying their decision … passed judgment concerning the rules of Faith” (n. 30). The modern view which reduces the authority of the Fathers to that of mere historical witnesses could not better be refuted.

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 circuмstances 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 the personal authority of the Fathers, with their position in the Church, with the amount of opposition to the doctrine, and with many other circuмstances.

The Consent of the Fathers does not always prove the Catholic character of a doctrine in the same way. If they distinctly state that a doctrine is a public dogma of the Church, the doctrine must be at once accepted. If they merely state that the doctrine is true and taught by the Church, without formally attributing to it the character of a dogma, this testimony has by no means the same weight. The doctrine thus attested cannot, on that account, be treated as a dogma. Nevertheless it is at least a Catholic truth and morally certain, and the denial of it would deserve the censure of temerity or error.

IV. The authority of the Fathers is held in high esteem by the Church in the interpretation of Scripture. They made the Bible their especial study, whereas later writers have not been so directly concerned with it, and when they have treated of it they have followed the lead of the Fathers. The consent of the Fathers is a positive and not an exclusive rule, i.e. the interpretation must be in accordance with it where it exists, but where it does not exist we may lawfully interpret even in opposition to the opinions of some of the Fathers. This consent must be gathered from all their writings and not merely from their commentaries, because in the latter they often have in view particular points of doctrine of a practical or ascetic nature, whereas in their other writings they are rather engaged in expounding Catholic dogma. But even in both kinds of writings a complete scientific exposition of the text can seldom be found, because, as a rule, the Fathers have in hand some particular doctrine which they endeavour to draw from and base upon the text. Hence the many apparent differences in their exegesis, which may, however, be easily explained by a collation of the various passages. (See supra, p. 65.)

SECT. 27.— The Writings of Theologians.

I. By Theologians we mean men learned in Theology, who as members or masters of the theological schools which came into existence after the patristic era, taught and handed down Catholic doctrine on strictly scientific lines, in obedience to and under the supervision of the bishops. The title belongs primarily to the Schoolmen of the Middle Ages — the Scholastic Theologians strictly so-called; then to all who followed the methods of the School during the last three centuries; and, generally, to all distinguished and approved writers on Theology whether they have adhered to the Scholastic methods or not. It is only in exceptional cases that the Church gives a public approbation to an individual Theologian, and this is done by canonization or by the still further honour of conferring on him the title of Doctor of the Church. When we speak of an Approved Author, we mean one who is held in general esteem on account of his learning and the Catholic spirit of his teaching. Some approved authors are of acknowledged weight, while others are of only minor importance. What we are about to state concerning the authority of Theologians must not be applied indiscriminately to every Catholic writer, but only to such as are weighty and approved (auctores probati et graves).

II. The authority of Theologians, like that of the Fathers, may be considered either individually and partially, or of the whole body collectively. As a rule, the authority of a single Theologian (with the exception of canonized Saints, and perhaps some authors of the greatest weight) does not create the presumption that no point of his doctrine was opposed to the common teaching of the Church in his day; much less that, independently of his reasons, the whole of his doctrine is positively probable merely on account of his authority. When, however, the majority of approved and weighty Theologians agree, it must be presumed that their teaching is not opposed to that of the Church. Moreover, if their doctrines are based upon sound arguments propounded without any prejudice and not contradicted very decidedly, the positive probability of the doctrines must be presumed. No more than this probability can be produced by the consent of many or even of all Theologians when they state a doctrine as a common opinion (opinio communis) and not as a common conviction (sententia conmunis). These questions have been discussed at great length by Moral Theologians in the controversy on Probabilism. See Lacroix, Theol. Mor., lib. I., tr. i., c. 2.

The consent of Theologians produces certainty that a doctrine is Catholic truth only when on the one hand the doctrine is proposed as absolutely certain, and on the other and the consent is universal and constant (Consensus universalis et constans non solurn opinionis sed firmae et ratae sententiae). If all agree that a particular doctrine is a Catholic dogma and that to deny it is heresy, then that doctrine is certainly a dogma. If they agree that a doctrine cannot be denied without injuring Catholic truth, and that such denial is deserving of censure, this again is a sure proof that the doctrine is in some way a Catholic doctrine. If, again, they agree in declaring that a doctrine is sufficiently certain and demonstrated, their consent is not indeed a formal proof of the Catholic character of the doctrine, nevertheless the existence of the consent shows that the doctrine belongs to the mind of the Church (catholicus intellectus), and that consequently its denial would incur the censure of rashness.

These principles on the authority of Theologians were strongly insisted on by Pius IX in the brief, Gravissimas inter (cf. infra, § 29), and they are evident consequences of the Catholic doctrine of Tradition. Although the assistance of the Holy Ghost is not directly promised to Theologians, nevertheless the assistance promised to the Church requires that He should prevent them as a body from falling into error; otherwise the Faithful who follow them would all be led astray. The consent of Theologians implies the consent of the Episcopate, according to St. Augustine's dictum: “Not to resist an error is to approve of it — not to defend a truth is to reject it.” (“Error cui non resistitur approbatur, et veritas quae non defenditur opprimitur “ (Decr. Grat., dist. 83, c. error). And even natural reason assures us that this consent is a guarantee of truth. “Whatever is found to be one and the same among many persons is not an error but a tradition” (Tertullian). (Supra, p. 68.)

The Church holds the mediaeval Doctors in almost the same esteem as the Fathers. The substance of the teaching of the Schoolmen and their method of treatment have both been strongly approved of by the Church (cf. Syllab., prop xiii., and Leo XIII., encyclical AEterni Patris on the study of St. Thomas).

[Editor: We have additionally, since this work was published, the evidence of the Code of Canon Law (1917) concerning St. Thomas, which confirms and even strengthens the point made by Scheeben in this place. "The study of philosophy and theology and the teaching of these sciences to their students must be accurately carried out by Professors (in seminaries etc.) according to the arguments, doctrine, and principles of St. Thomas which they are inviolately to hold." CIC 1366, 2.]

The consent of Theologians produces certainty that a doctrine is Catholic truth only when on the one hand the doctrine is proposed as absolutely certain, and on the other and the consent is universal and constant (Consensus universalis et constans non solurn opinionis sed firmae et ratae sententiae). If all agree that a particular doctrine is a Catholic dogma and that to deny it is heresy, then that doctrine is certainly a dogma. If they agree that a doctrine cannot be denied without injuring Catholic truth, and that such denial is deserving of censure, this again is a sure proof that the doctrine is in some way a Catholic doctrine. If, again, they agree in declaring that a doctrine is sufficiently certain and demonstrated, their consent is not indeed a formal proof of the Catholic character of the doctrine, nevertheless the existence of the consent shows that the doctrine belongs to the mind of the Church (catholicus intellectus), and that consequently its denial would incur the censure of rashness.

These principles on the authority of Theologians were strongly insisted on by Pius IX in the brief, Gravissimas inter (cf. infra, § 29), and they are evident consequences of the Catholic doctrine of Tradition. Although the assistance of the Holy Ghost is not directly promised to Theologians, nevertheless the assistance promised to the Church requires that He should prevent them as a body from falling into error; otherwise the Faithful who follow them would all be led astray. The consent of Theologians implies the consent of the Episcopate, according to St. Augustine's dictum: “Not to resist an error is to approve of it — not to defend a truth is to reject it.” (“Error cui non resistitur approbatur, et veritas quae non defenditur opprimitur “ (Decr. Grat., dist. 83, c. error). And even natural reason assures us that this consent is a guarantee of truth. “Whatever is found to be one and the same among many persons is not an error but a tradition” (Tertullian). (Supra, p. 68.)

Sorry to disappoint you but St. Alphonsus does not have the authority to declare anything is de fide.

What you have NEVER done is provided even one theologian who noticed and commented on the "grave error" you have discovered. That's because it's not an error, it is true and the teaching of the Church.