Nobility is not a mark of a divine vocation. [...] We must consider not nobility of blood, but sanctity of life (St. Jerome, In Tit., i). St. Gregory says the same: "By one's conduct, not by one's high birth, is one's vocation proved."
Nor is the will of the parents a mark of a divine vocation. [...] "How many mothers," says St. John Chrysostom, [...] "have eyes only for the bodies of their children and disdain their souls! To see them happy here below is all that they desire; as for the punishments that perhaps their children are to endure in the next life, they do not even think of them" (Hom. 35). [...] We have no enemies more dangerous than our own relatives. [...]
St. Thomas expressly teaches that in the choice of a state of life children are not obliged to obey their parents. And the saint says that when there is a question of a vocation to religion, a person is not bound even to consult his relatives. [cf. Contra retr. a rel., ch. 9]. [...]
Nor is talent or fitness for the offices of a priest a sign of vocation, for along with talent a holy life and a divine call are necessary. What, then, are the marks of a divine vocation to the ecclesiastical state? There are three principal marks:
I. PURITY OF INTENTION.
The first is a good intention. It is necessary to enter the sanctuary by the door, but there is no other door than Jesus Christ: I am the door of the sheep.... If any man enter in, he shall be saved (Jn. 10:7). To enter, then, by the door is to become a priest not to please relatives, nor to advance the family, nor for the sake of self-interest or self-esteem, but to serve God, to propagate his glory, and to save souls. "If any one," says a wise theologian, the learned continuator of Tournely, "presents himself for holy Orders without any vicious affection, and with the sole desire to be employed in the service of God and in the salvation of his neighbor, he, we may believe, is called by God" (De Ord., q. 4, a. 4). Another author asserts that he who is impelled by ambition, interest, or a motive of his own glory, is called not by God, but by the devil. "But," adds St. Anselm, "he who enters the priesthood through so unworthy motives shall receive not a blessing but a malediction from God" (In Heb. 5).
2. SCIENCE AND TALENTS.
The second mark is the talent and learning necessary for the fulfillment of the duties of a priest. Priests must be masters to teach the people the law of God. For the lips of the priest shall keep knowledge, and they shall seek the law at his mouth (Mal. 2:7). Sidonius Apollinarius used to say: "Ignorant physicians are the cause of many deaths" (Lib. 2, ep. 12). An ignorant priest, particularly a confessor, who teaches false doctrines and gives bad counsels will be the ruin of many souls; because, in consequence of being a priest, his errors are easily believed. Hence Ivone Carnotensis has written: "No one should be admitted to holy Orders unless he has given sufficient proofs of good conduct and learning."
3. POSITIVE GOODNESS OF CHARACTER.
The third mark of an ecclesiastical vocation is positive virtue. Hence, in the first place, the person who is to be ordained should be a man of innocent life, and should not be contaminated by sins. The Apostle requires that they who are to be ordained priests should be free from every crime. In ancient times a person who had committed a single mortal sin could never be ordained, as we learn from the First Council of Nice (Canon 9: "Qui confessi sunt peccata, canon (ecclesiasticus ordo) non admittit). And St. Jerome says that it was not enough for a person to be free from sin at the time of his ordination, but that it was, moreover, necessary that he should not have fallen into mortal sin since the time of his baptism (In Tit. 1). It is true that this rigorous discipline has ceased in the Church, but it has always been at least required that he who had fallen into grievous sins should purify his conscience for a considerable time before his ordination. This we may infer from a letter to the Archbishop of Rheims, in which Alexander III commanded that a deacon who had wounded another deacon, if he sincerely repented of his sin, might, after being absolved, and after performing the penance enjoined, be permitted again to exercise his Order; and that if he afterwards led a perfect life, he might be promoted to priesthood (De diacono. Qui cler., ch. 1). He, then, who finds himself bound by a habit of any vice cannot take any holy Order without incurring the guilt of mortal sin. "I am horrified," says St. Bernard (Epist. 8), "when I think whence thou comest, whither thou goest, and what a short penance thou hast put between thy sins and thy ordination. However, it is indispensable that thou do not undertake to purify the conscience of others before thou purifiest thy own."
Of those daring sinners who, though full of bad habits, take priesthood, an ancient author, Gildas, says, "It is not to the priesthood that they should be admitted, but they should be dragged to the pillory." They, then, says St. Isidore, who are still subject to the habit of any sin should not be promoted to holy Orders (Sent. 1.3, ch. 34).
But he who intends to ascend the altar must not only be free from sin, but must have also begun to walk in the path of perfection, and have acquired a habit of virtue. In our Moral Theology (1.6, n. 63, etc.) we have shown in a distinct dissertation (and this is the common opinion) that if a person in the habit of any vice wish to be ordained, it is not enough for him to have the dispositions necessary for the sacrament of penance, but that he must also have the dispositions required for receiving the sacrament of order; otherwise he is unfit for both; and should he receive absolution with the intention of taking Orders without the necessary dispositions, he and the confessor who absolves him shall be guilty of a grievous sin. For it is not enough for those who wish to take holy Orders to have left the state of sin, they must also, according to the words of Alexander III, cited in the preceding paragraph, have the positive virtue necessary for the ecclesiastical state. From the words of the Pontiff we learn that a person who has done penance may exercise an order already received, but he who has only done penance cannot take a higher order.
The angelic Doctor teaches the same doctrine: "Sanctity is required for the reception of holy Orders, and we must place the sublime burden on the priesthood only upon walls already dried by sanctity; that is freed from the malignant humor of sin" (S.Th., 2.2.189.1). This is conformable to what St. Denis wrote long before: "Let no one be so bold as to propose himself to others as their guide in the things of God, if he has not first, with all his power, transformed himself into God to the point of perfect resemblance to him" (De Eccl. Hier., ch. 3). For this St. Thomas adduces two reasons: the first is, that as he who takes orders is raised above seculars in dignity, so he should be superior to them in sanctity (Suppl., 35.1). The second reason is, that by his ordination a priest is appointed to exercise the most sublime ministry on the altar, for which greater sanctity is required than for the religious state (S.Th., 2.2.184.8).
Hence the Apostle forbade Timothy to ordain neophytes; that is, according to St. Thomas, neophytes in perfection as well as neophytes in age.
Hence the Council of Trent, in reference to the words of Scripture, And a spotless life in old age (Wis. 4:9), prescribes to the bishops to admit to ordination only those who show themselves worthy by a conduct full of wise maturity (Sess. 23, ch. 12). And of this positive virtue it is necessary, according to St. Thomas, to have not a doubtful but a certain knowledge (Suppl., 36.4). This, according to St. Gregory, is particularly necessary with regard to the virtue of chastity: "No one should be admitted to the ministry of the altar unless an assurance has been given of his perfect chastity" (Lib. 1, ep. 42). With regard to chastity, the holy Pontiff required a proof of many years (Lib. 3, ep. 26).
From this we may infer that God will demand a terrible account of the parish priest who gives to persons aspiring to the priesthood a testimony of their having frequented the sacraments and led exemplary lives, though they had neglected the frequentation of the sacraments, and had given scandal rather than good example. Such parish priests by the false attestations, given not through charity, as they pretend, but against the charity due to God and the Church, render themselves guilty of all the sins that shall afterwards be committed by the bad priests who were ordained in consequence of these testimonials. For in this matter bishops trust to the testimony of parish priests, and are deceived. Nor should a parish priest in giving such attestations trust the testimony of others; he cannot give them unless he is certain that what he attests is true, namely, that the ecclesiastic has really led an exemplary life, and has frequented the sacraments.
And as a bishop cannot ordain any person unless he be a man of approved chastity, so a confessor cannot permit an incontinent penitent to receive ordination without having a moral certainty that he is free from the bad habit which he had contracted, and that he had acquired a habit of the virtue of chastity.
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Source: St. Alphonsus Liguori, The Dignity and Duties of the Priest, ed. by Eugene Grimm (New York, NY), http://wallmell.webs.com/LiguoriDignityDutiesPriest.pdf, chapter 10.
2. SCIENCE AND TALENTS.
The second mark is the talent and learning necessary for the fulfillment of the duties of a priest. Priests must be masters to teach the people the law of God. For the lips of the priest shall keep knowledge, and they shall seek the law at his mouth (Mal. 2:7). Sidonius Apollinarius used to say: "Ignorant physicians are the cause of many deaths" (Lib. 2, ep. 12). An ignorant priest, particularly a confessor, who teaches false doctrines and gives bad counsels will be the ruin of many souls; because, in consequence of being a priest, his errors are easily believed. Hence Ivone Carnotensis has written: "No one should be admitted to holy Orders unless he has given sufficient proofs of good conduct and learning."
3. POSITIVE GOODNESS OF CHARACTER.
The third mark of an ecclesiastical vocation is positive virtue. Hence, in the first place, the person who is to be ordained should be a man of innocent life, and should not be contaminated by sins. The Apostle requires that they who are to be ordained priests should be free from every crime. In ancient times a person who had committed a single mortal sin could never be ordained, as we learn from the First Council of Nice (Canon 9: "Qui confessi sunt peccata, canon (ecclesiasticus ordo) non admittit). And St. Jerome says that it was not enough for a person to be free from sin at the time of his ordination, but that it was, moreover, necessary that he should not have fallen into mortal sin since the time of his baptism (In Tit. 1). It is true that this rigorous discipline has ceased in the Church, but it has always been at least required that he who had fallen into grievous sins should purify his conscience for a considerable time before his ordination. This we may infer from a letter to the Archbishop of Rheims, in which Alexander III commanded that a deacon who had wounded another deacon, if he sincerely repented of his sin, might, after being absolved, and after performing the penance enjoined, be permitted again to exercise his Order; and that if he afterwards led a perfect life, he might be promoted to priesthood (De diacono. Qui cler., ch. 1). He, then, who finds himself bound by a habit of any vice cannot take any holy Order without incurring the guilt of mortal sin. "I am horrified," says St. Bernard (Epist. 8), "when I think whence thou comest, whither thou goest, and what a short penance thou hast put between thy sins and thy ordination. However, it is indispensable that thou do not undertake to purify the conscience of others before thou purifiest thy own."
Of those daring sinners who, though full of bad habits, take priesthood, an ancient author, Gildas, says, "It is not to the priesthood that they should be admitted, but they should be dragged to the pillory." They, then, says St. Isidore, who are still subject to the habit of any sin should not be promoted to holy Orders (Sent. 1.3, ch. 34).
But he who intends to ascend the altar must not only be free from sin, but must have also begun to walk in the path of perfection, and have acquired a habit of virtue. In our Moral Theology (1.6, n. 63, etc.) we have shown in a distinct dissertation (and this is the common opinion) that if a person in the habit of any vice wish to be ordained, it is not enough for him to have the dispositions necessary for the sacrament of penance, but that he must also have the dispositions required for receiving the sacrament of order; otherwise he is unfit for both; and should he receive absolution with the intention of taking Orders without the necessary dispositions, he and the confessor who absolves him shall be guilty of a grievous sin. For it is not enough for those who wish to take holy Orders to have left the state of sin, they must also, according to the words of Alexander III, cited in the preceding paragraph, have the positive virtue necessary for the ecclesiastical state. From the words of the Pontiff we learn that a person who has done penance may exercise an order already received, but he who has only done penance cannot take a higher order.
The angelic Doctor teaches the same doctrine: "Sanctity is required for the reception of holy Orders, and we must place the sublime burden on the priesthood only upon walls already dried by sanctity; that is freed from the malignant humor of sin" (S.Th., 2.2.189.1). This is conformable to what St. Denis wrote long before: "Let no one be so bold as to propose himself to others as their guide in the things of God, if he has not first, with all his power, transformed himself into God to the point of perfect resemblance to him" (De Eccl. Hier., ch. 3). For this St. Thomas adduces two reasons: the first is, that as he who takes orders is raised above seculars in dignity, so he should be superior to them in sanctity (Suppl., 35.1). The second reason is, that by his ordination a priest is appointed to exercise the most sublime ministry on the altar, for which greater sanctity is required than for the religious state (S.Th., 2.2.184.8).
Hence the Apostle forbade Timothy to ordain neophytes; that is, according to St. Thomas, neophytes in perfection as well as neophytes in age.
Hence the Council of Trent, in reference to the words of Scripture, And a spotless life in old age (Wis. 4:9), prescribes to the bishops to admit to ordination only those who show themselves worthy by a conduct full of wise maturity (Sess. 23, ch. 12). And of this positive virtue it is necessary, according to St. Thomas, to have not a doubtful but a certain knowledge (Suppl., 36.4). This, according to St. Gregory, is particularly necessary with regard to the virtue of chastity: "No one should be admitted to the ministry of the altar unless an assurance has been given of his perfect chastity" (Lib. 1, ep. 42). With regard to chastity, the holy Pontiff required a proof of many years (Lib. 3, ep. 26).
From this we may infer that God will demand a terrible account of the parish priest who gives to persons aspiring to the priesthood a testimony of their having frequented the sacraments and led exemplary lives, though they had neglected the frequentation of the sacraments, and had given scandal rather than good example. Such parish priests by the false attestations, given not through charity, as they pretend, but against the charity due to God and the Church, render themselves guilty of all the sins that shall afterwards be committed by the bad priests who were ordained in consequence of these testimonials. For in this matter bishops trust to the testimony of parish priests, and are deceived. Nor should a parish priest in giving such attestations trust the testimony of others; he cannot give them unless he is certain that what he attests is true, namely, that the ecclesiastic has really led an exemplary life, and has frequented the sacraments.
And as a bishop cannot ordain any person unless he be a man of approved chastity, so a confessor cannot permit an incontinent penitent to receive ordination without having a moral certainty that he is free from the bad habit which he had contracted, and that he had acquired a habit of the virtue of chastity.
---
Source: St. Alphonsus Liguori, The Dignity and Duties of the Priest, ed. by Eugene Grimm (New York, NY), http://wallmell.webs.com/LiguoriDignityDutiesPriest.pdf, chapter 10.