Summa Th. II-II EN Qu.189 a.2
Objection: 1. It would seem that one ought not to be bound by vow to enter religion. For in making his profession a man is bound by the religious vow. Now before profession a year of probation is allowed, according to the rule of the Blessed Benedict (lviii) and according to the decree of Innocent IV [*Sext. Decret., cap. Non solum., de Regular. et Transeunt, ad Relig.] who moreover forbade anyone to be bound to the religious life by profession before completing the year of probation. Therefore it would seem that much less ought anyone while yet in the world to be bound by vow to enter religion.
2. Further, Gregory says (Regist. xi, Ep 15): Jews "should be persuaded to be converted, not by compulsion but of their own free will" (Dist. xlv, can. De Judaeis). Now one is compelled to fulfil what one has vowed. Therefore no one should be bound by vow to enter religion.
3. Further, no one should give another an occasion of falling; wherefore it is written (Ex 21,33-34): "If a man open a pit . . . and an ox or an ass fall into it, the owner of the pit shall pay the price of the beasts." Now through being bound by vow to enter religion it often happens that people fall into despair and various sins. Therefore it would seem that one ought not to be bound by vow to enter religion.
On the contrary It is written, (Ps 75,12): "Vow ye, and pay to the Lord your God"; and a gloss of Augustine says that "some vows concern the individual, such as vows of chastity, virginity, and the like." Consequently Holy Scripture invites us to vow these things. But Holy Scripture invites us only to that which is better. Therefore it is better to bind oneself by vow to enter religion.
I answer that As stated above (Question , Article ), when we were treating of vows, one and the same work done in fulfilment of a vow is more praiseworthy than if it be done apart from a vow, both because to vow is an act of religion, which has a certain pre-eminence among the virtues, and because a vow strengthens a man's will to do good; and just as a sin is more grievous through proceeding from a will obstinate in evil, so a good work is the more praiseworthy through proceeding from a will confirmed in good by means of a vow. Therefore it is in itself praiseworthy to bind oneself by vow to enter religion.
Reply to Objection: 1. The religious vow is twofold. One is the solemn vow which makes a man a monk or a brother in some other religious order. This is called the profession, and such a vow should be preceded by a year's probation, as the objection proves. The other is the simple vow which does not make a man a monk or a religious, but only binds him to enter religion, and such a vow need not be preceded by a year's probation.
2. The words quoted from Gregory must be understood as referring to absolute violence. But the compulsion arising from the obligation of a vow is not absolute necessity, but a necessity of end, because after such a vow one cannot attain to the end of salvation unless one fulfil that vow. Such a necessity is not to be avoided; indeed, as Augustine says (Ep. cxxvii ad Armentar. et Paulin.), "happy is the necessity that compels us to better things."
3. The vow to enter religion is a strengthening of the will for better things, and consequently, considered in itself, instead of giving a man an occasion of falling, withdraws him from it. But if one who breaks a vow falls more grievously, this does not derogate from the goodness of the vow, as neither does it derogate from the goodness of Baptism that some sin more grievously after being baptized.
Objection: 1. It would seem that one who is bound by the vow to enter religion is not under an obligation of entering religion. For it is said in the Decretals (XVII, qu. ii, can. Consaldus): "Consaldus, a priest under pressure of sickness and emotional fervour, promised to become a monk. He did not, however, bind himself to a monastery or abbot; nor did he commit his promise to writing, but he renounced his benefice in the hands of a notary; and when he was restored to health he refused to become a monk." And afterwards it is added: "We adjudge and by apostolic authority we command that the aforesaid priest be admitted to his benefice and sacred duties, and that he be allowed to retain them in peace." Now this would not be if he were bound to enter religion. Therefore it would seem that one is not bound to keep one's vow of entering religion.
2. Further, no one is bound to do what is not in his power. Now it is not in a person's power to enter religion, since this depends on the consent of those whom he wishes to join. Therefore it would seem that a man is not obliged to fulfil the vow by which he bound himself to enter religion.
3. Further, a less useful vow cannot remit a more useful one. Now the fulfilment of a vow to enter religion might hinder the fulfilment of a vow to take up the cross in defense of the Holy Land; and the latter apparently is the more useful vow, since thereby a man obtains the forgiveness of his sins. Therefore it would seem that the vow by which a man has bound himself to enter religion is not necessarily to be fulfilled.
On the contrary It is written (Qo 5,3): "If thou hast vowed anything to God, defer not to pay it, for an unfaithful and foolish promise displeaseth him"; and a gloss on Ps 75,12, "Vow ye, and pay to the Lord your God," says: "To vow depends on the will: but after the vow has been taken the fulfilment is of obligation."
I answer that As stated above (Question , Article ), when we were treating of vows, a vow is a promise made to God in matters concerning God. Now, as Gregory says in a letter to Boniface [*Innoc. I, Epist. ii, Victricio Epo. Rotomag., cap. 14; Cf. can. Viduas: cause. xxvii, qu. 1]: "If among men of good faith contracts are wont to be absolutely irrevocable, how much more shall the breaking of this promise given to God be deserving of punishment!" Therefore a man is under an obligation to fulfil what he has vowed, provided this be something pertaining to God.Now it is evident that entrance into religion pertains very much to God, since thereby man devotes himself entirely to the divine service, as stated above (Question , Article ). Hence it follows that he who binds himself to enter religion is under an obligation to enter religion according as he intends to bind himself by his vow: so that if he intend to bind himself absolutely, he is obliged to enter as soon as he can, through the cessation of a lawful impediment; whereas if he intend to bind himself to a certain fixed time, or under a certain fixed condition, he is bound to enter religion when the time comes or the condition is fulfilled.
Reply to Objection: 1. This priest had made, not a solemn, but a simple vow. Hence he was not a monk in effect, so as to be bound by law to dwell in a monastery and renounce his cure. However, in the court of conscience one ought to advise him to renounce all and enter religion. Hence (Extra, De Voto et Voti Redemptione, cap. Per tuas) the Bishop of Grenoble, who had accepted the episcopate after vowing to enter religion, without having fulfilled his vow, is counseled that if "he wish to heal his conscience he should renounce the government of his see and pay his vows to the Most High."
2. As stated above (Question , Article , ad 2), when we were treating of vows, he who has bound himself by vow to enter a certain religious order is bound to do what is in his power in order to be received in that order; and if he intend to bind himself simply to enter the religious life, if he be not admitted to one, he is bound to go to another; whereas if he intend to bind himself only to one particular order, he is bound only according to the measure of the obligation to which he has engaged himself.
3. The vow to enter religion being perpetual is greater than the vow of pilgrimage to the Holy Land, which is a temporal vow; and as Alexander III says (Extra, De Voto et Voti Redemptione, cap. Scripturae), "he who exchanges a temporary service for the perpetual service of religion is in no way guilty of breaking his vow."Moreover it may be reasonably stated that also by entrance into religion a man obtains remission of all his sins. For if by giving alms a man may forthwith satisfy for his sins, according to Da 4,24, "Redeem thou thy sins with alms," much more does it suffice to satisfy for all his sins that a man devote himself wholly to the divine service by entering religion, for this surpasses all manner of satisfaction, even that of public penance, according to the Decretals (XXXIII, qu. i, cap. Admonere) just as a holocaust exceeds a sacrifice, as Gregory declares (Hom. xx in Ezech.). Hence we read in the Lives of the Fathers (vi, 1) that by entering religion one receives the same grace as by being baptized. And yet even if one were not thereby absolved from all debt of punishment, nevertheless the entrance into religion is more profitable than a pilgrimage to the Holy Land, as regards the advancement in good, which is preferable to absolution from punishment.
Objection: 1. It would seem that he who has vowed to enter religion, is bound in perpetuity to remain in religion. For it is better not to enter religion than to leave after entering, according to 2P 2,21, "It had been better for them not to have known the way of justice, than after they have known it to turn back," and Lc 9,62, "No man putting his hand to the plough, and looking back, is fit for the kingdom of God." But he who bound himself by the vow to enter religion, is under the obligation to enter, as stated above (Article ). Therefore he is also bound to remain for always.
2. Further, everyone is bound to avoid that which gives rise to scandal, and is a bad example to others. Now by leaving after entering religion a man gives a bad example and is an occasion of scandal to others, who are thereby withdrawn from entering or incited to leave. Therefore it seems that he who enters religion in order to fulfil a vow which he had previously taken, is bound to remain evermore.
3. Further, the vow to enter religion is accounted a perpetual vow: wherefore it is preferred to temporal vows, as stated above (Article , ad 3; Question , Article , ad 1). But this would not be so if a person after vowing to enter religion were to enter with the intention of leaving. It seems, therefore, that he who vows to enter religion is bound also to remain in perpetuity.
On the contrary The vow of religious profession, for the reason that it binds a man to remain in religion for evermore, has to be preceded by a year of probation; whereas this is not required before the simple vow whereby a man binds himself to enter religion. Therefore it seems that he who vows to enter religion is not for that reason bound to remain there in perpetuity.
I answer that The obligation of a vow proceeds from the will: because "to vow is an act of the will" according to Augustine [*Gloss of Peter Lombard on Ps 75,12]. Consequently the obligation of a vow extends as far as the will and intention of the person who takes the vow. Accordingly if in vowing he intend to bind himself not only to enter religion, but also to remain there evermore, he is bound to remain in perpetuity. If, on the other hand, he intend to bind himself to enter religion for the purpose of trial, while retaining the freedom to remain or not remain, it is clear that he is not bound to remain. If, however, in vowing he thought merely of entering religion, without thinking of being free to leave, or of remaining in perpetuity, it would seem that he is bound to enter religion according to the form prescribed by common law, which is that those who enter should be given a year's probation. Wherefore he is not bound to remain for ever.
Reply to Objection: 1. It is better to enter religion with the purpose of making a trial than not to enter at all, because by so doing one disposes oneself to remain always. Nor is a person accounted to turn or to look back, save when he omits to do that which he engaged to do: else whoever does a good work for a time, would be unfit for the kingdom of God, unless he did it always, which is evidently false.
2. A man who has entered religion gives neither scandal nor bad example by leaving, especially if he do so for a reasonable motive; and if others are scandalized, it will be passive scandal on their part, and not active scandal on the part of the person leaving, since in doing so, he has done what was lawful, and expedient on account of some reasonable motive, such as sickness, weakness, and the like.
3. He who enters with the purpose of leaving forthwith, does not seem to fulfil his vow, since this was not his intention in vowing. Hence he must change that purpose, at least so as to wish to try whether it is good for him to remain in religion, but he is not bound to remain for evermore.
Objection: 1. It would seem that children ought not to be received in religion. Because it is said (Extra, De Regular. et Transeunt. ad Relig., cap. Nullus): "No one should be tonsured unless he be of legal age and willing." But children, seemingly, are not of legal age; nor have they a will of their own, not having perfect use of reason. Therefore it seems that they ought not to be received in religion.
2. Further, the state of religion would seem to be a state of repentance; wherefore religion is derived [*Cf. Question , Article ] from "religare" [to bind] or from "re-eligere" [to choose again], as Augustine says (De Civ. Dei x, 3 [*Cf. De Vera Relig. lv]). But repentance does not become children. Therefore it seems that they should not enter religion.
3. Further, the obligation of a vow is like that of an oath. But children under the age of fourteen ought not to be bound by oath (Decret. XXII, qu. v, cap. Pueri and cap. Honestum.). Therefore it would seem that neither should they be bound by vow.
4. Further, it is seemingly unlawful to bind a person to an obligation that can be justly canceled. Now if any persons of unripe age bind themselves to religion, they can be withdrawn by their parents or guardians. For it is written in the Decretals (XX, qu. ii, can. Puella) that "if a maid under twelve years of age shall take the sacred veil of her own accord, her parents or guardians, if they choose, can at once declare the deed null and void." It is therefore unlawful for children, especially of unripe age, to be admitted or bound to religion.
On the contrary our Lord said (Mt 19,14): "Suffer the little children, and forbid them not to come to Me." Expounding these words Origen says (Tract. vii in Matth.) that "the disciples of Jesus before they have been taught the conditions of righteousness [*Cf. Mt 19,16-30], rebuke those who offer children and babes to Christ: but our Lord urges His disciples to stoop to the service of children. We must therefore take note of this, lest deeming ourselves to excel in wisdom we despise the Church's little ones, as though we were great, and forbid the children to come to Jesus."
I answer that As stated above (Article , ad 1), the religious vow is twofold. One is the simple vow consisting in a mere promise made to God, and proceeding from the interior deliberation of the mind. Such a vow derives its efficacy from the divine law. Nevertheless it may encounter a twofold obstacle. First, through lack of deliberation, as in the case of the insane, whose vows are not binding [*Extra, De Regular. et Transeunt. ad Relig., cap. Sicut tenor]. The same applies to children who have not reached the required use of reason, so as to be capable of guile, which use boys attain, as a rule, at about the age of fourteen, and girls at the age of twelve, this being what is called "the age of puberty," although in some it comes earlier and in others it is delayed, according to the various dispositions of nature. Secondly, the efficacy of a simple vow encounters an obstacle, if the person who makes a vow to God is not his own master; for instance, if a slave, though having the use of reason, vows to enter religion, or even is ordained, without the knowledge of his master: for his master can annul this, as stated in the Decretals (Dist. LIV, cap. Si servus). And since boys and girls under the age of puberty are naturally in their father's power as regards the disposal of their manner of life, their father may either cancel or approve their vow, if it please him to do so, as it is expressly said with regard to a woman (Nb 30,4).Accordingly if before reaching the age of puberty a child makes a simple vow, not yet having full use of reason, he is not bound in virtue of the vow; but if he has the use of reason before reaching the age of puberty, he is bound, so far as he is concerned, by his vow; yet this obligation may be removed by his father's authority, under whose control he still remains, because the ordinance of the law whereby one man is subject to another considers what happens in the majority of cases. If, however, thechild has passed the age of puberty, his vow cannot be annulled by the authority of his parents; though if he has not the full use of reason, he would not be bound in the sight of God.The other is the solemn vow which makes a man a monk or a religious. Such a vow is subject to the ordinance of the Church, on account of the solemnity attached to it. And since the Church considers what happens in the majority of cases, a profession made before the age of puberty, however much the person who makes profession may have the use of reason, or be capable of guile, does not take effect so as to make him a religious (Extra, De Regular., etc. cap. Significatum est.).Nevertheless, although they cannot be professed before the age of puberty, they can, with the consent of their parents, be received into religion to be educated there: thus it is related of John the Baptist (Lc 1,80) that "the child grew and was strengthened in spirit, and was in the deserts." Hence, as Gregory states (Dial. ii, 3), "the Roman nobles began to give their sons to the blessed Benedict to be nurtured for Almighty God"; and this is most fitting, according to Lam. 3:27, "It is good for a man when he has borne the yoke from his youth." It is for this reason that by common custom children are made to apply themselves to those duties or arts with which they are to pass their lives.
Reply to Objection: 1. The legal age for receiving the tonsure and taking the solemn vow of religion is the age of puberty, when a man is able to make use of his own will; but before the age of puberty it is possible to have reached the lawful age to receive the tonsure and be educated in a religious house.
2. The religious state is chiefly directed to the attachment of perfection, as stated above (Question , Article , ad 4); and accordingly it is becoming to children, who are easily drawn to it. But as a consequence it is called a state of repentance, inasmuch as occasions of sin are removed by religious observances, as stated above (Question , Article , ad 4).
3. Even as children are not bound to take oaths (as the canon states), so are they not bound to take vows. If, however, they bind themselves by vow or oath to do something, they are bound in God's sight, if they have the use of reason, but they are not bound in the sight of the Church before reaching the age of fourteen.
4. A woman who has not reached the age of puberty is not rebuked (Nb 30,4) for taking a vow without her parents' consent: but the vow can be made void by her parents. Hence it is evident that she does not sin in vowing. But we are given to understand that she binds herself by vow, so far as she may, without prejudice to her parents' authority.
Objection: 1. It would seem that one ought to be withdrawn from entering religion through deference to one's parents. For it is not lawful to omit that which is of obligation in order to do that which is optional. Now deference to one's parents comes under an obligation of the precept concerning the honoring of our parents (Ex 20,12); wherefore the Apostle says (1Tm 5,4): "If any widow have children or grandchildren, let her learn first to govern her own house, and to make a return of duty to her parents." But the entrance to religion is optional. Therefore it would seem that one ought not to omit deference to one's parents for the sake of entering religion.
2. Further, seemingly the subjection of a son to his father is greater than that of a slave to his master, since sonship is natural, while slavery results from the curse of sin, as appears from Gn 9,25. Now a slave cannot set aside the service of his master in order to enter religion or take holy orders, as stated in the Decretals (Dist. LIV, cap. Si servus). Much less therefore can a son set aside the deference due to his father in order to enter religion.
3. Further, a man is more indebted to his parents than to those to whom he owes money. Now persons who owe money to anyone cannot enter religion. For Gregory says (Regist. viii, Ep 5) that "those who are engaged in trade must by no means be admitted into a monastery, when they seek admittance, unless first of all they withdraw from public business" (Dist. liii, can. Legem.). Therefore seemingly much less may children enter religion in despite of their duty to their parents.
On the contrary It is related (Mt 4,22) that James and John "left their nets and father, and followed our Lord." By this, says Hilary (Can. iii in Matth.), "we learn that we who intend to follow Christ are not bound by the cares of the secular life, and by the ties of home."
I answer that As stated above (Question , Article , ad 2) when we were treating of piety, parents as such have the character of a principle, wherefore it is competent to them as such to have the care of their children. Hence it is unlawful for a person having children to enter religion so as altogether to set aside the care for their children, namely without providing for their education. For it is written (1Tm 5,8) that "if any man have not care of his own . . . he hath denied the faith, and is worse than an infidel."Nevertheless it is accidentally competent to parents to be assisted by their children, in so far, to wit, as they are placed in a condition of necessity. Consequently we must say that when their parents are in such need that they cannot fittingly be supported otherwise than by the help of their children, these latter may not lawfully enter religion in despite of their duty to their parents. If, however, the parents' necessity be not such as to stand in great need of their children's assistance, the latter may, in despite of the duty they owe their parents, enter religion even against their parents' command, because after the age of puberty every freeman enjoys freedom in things concerning the ordering of his state of life, especially in such as belong to the service of God, and "we should more obey the Father of spirits that we may live [*'Shall we not much more obey the Father of Spirits, and live?']," as says the Apostle (He 12,9), than obey our parents. Hence as we read (Mt 8,22 Lc 9,62) our Lord rebuked the disciple who was unwilling to follow him forthwith on account of his father's burial: for there were others who could see to this, as Chrysostom remarks [*Hom. xxvii in Matth.].
Reply to Objection: 1. The commandment of honoring our parents extends not only to bodily but also to spiritual service, and to the paying of deference. Hence even those who are in religion can fulfil the commandment of honoring their parents, by praying for them and by revering and assisting them, as becomes religious, since even those who live in the world honor their parents in different ways as befits their condition.
2. Since slavery was imposed in punishment of sin, it follows that by slavery man forfeits something which otherwise he would be competent to have, namely the free disposal of his person, for "a slave belongs wholly to his master" [*Aristotle, Polit. i, 2]. On the other hand, the son, through being subject to his father, is not hindered from freely disposing of his person by transferring himself to the service of God; which is most conducive to man's good.
3. He who is under a certain fixed obligation cannot lawfully set it aside so long as he is able to fulfil it. Wherefore if a person is under an obligation to give an account to someone or to pay a certain fixed debt, he cannot lawfully evade this obligation in order to enter religion. If, however, he owes a sum of money, and has not wherewithal to pay the debt, he must do what he can, namely by surrendering his goods to his creditor. According to civil law [*Cod. IV, x, de Oblig. et Action, 12] money lays an obligation not on the person of a freeman, but on his property, because the person of a freeman "is above all pecuniary consideration" [*Dig. L, xvii, de div. reg. Jur. ant. 106,176]. Hence, after surrendering his property, he may lawfully enter religion, nor is he bound to remain in the world in order to earn the means of paying the debt.On the other hand, he does not owe his father a special debt, except as may arise in a case of necessity, as stated above.
Objection: 1. It would seem that parish priests cannot lawfully enter religion. For Gregory says (Past. iii, 4) that "he who undertakes the cure of souls, receives an awful warning in the words: 'My son, if thou be surety for thy friend, thou hast engaged fast thy hand to a stranger'" (Pr 6,1); and he goes on to say, "because to be surety for a friend is to take charge of the soul of another on the surety of one's own behavior." Now he who is under an obligation to a man for a debt, cannot enter religion, unless he pay what he owes, if he can. Since then a priest is able to fulfil the cure of souls, to which obligation he has pledged his soul, it would seem unlawful for him to lay aside the cure of souls in order to enter religion.
2. Further, what is lawful to one is likewise lawful to all. But if all priests having cure of souls were to enter religion, the people would be left without a pastor's care, which would be unfitting. Therefore it seems that parish priests cannot lawfully enter religion.
3. Further, chief among the acts to which religious orders are directed are those whereby a man gives to others the fruit of his contemplation. Now such acts are competent to parish priests and archdeacons, whom it becomes by virtue of their office to preach and hear confessions. Therefore it would seem unlawful for a parish priest or archdeacon to pass over to religion.
On the contrary It is said in the Decretals (XIX, qu. ii, cap. Duce sunt leges.): "If a man, while governing the people in his church under the bishop and leading a secular life, is inspired by the Holy Ghost to desire to work out his salvation in a monastery or under some canonical rule, even though his bishop withstand him, we authorize him to go freely."
I answer that As stated above (Article , ad 3; Question , Article , ad 1), the obligation of a perpetual vow stands before every other obligation. Now it belongs properly to bishops and religious to be bound by perpetual vow to devote themselves to the divine service [*Cf. Question , Article ], while parish priests and archdeacons are not, as bishops are, bound by a perpetual and solemn vow to retain the cure of souls. Wherefore bishops "cannot lay aside their bishopric for any pretext whatever, without the authority of the Roman Pontiff" (Extra, De Regular. et Transeunt. ad Relig., cap. Licet.): whereas archdeacons and parish priests are free to renounce in the hands of the bishop the cure entrusted to them, without the Pope's special permission, who alone can dispense from perpetual vows. Therefore it is evident that archdeacons and parish priests may lawfully enter religion.
Reply to Objection: 1. Parish priests and archdeacons have bound themselves to the care of their subjects, as long as they retain their archdeaconry or parish, but they did not bind themselves to retain their archdeaconry or parish for ever.
2. As Jerome says (Contra Vigil.): "Although they," namely religious, "are sorely smitten by thy poisonous tongue, about whom you argue, saying; 'If all shut themselves up and live in solitude, who will go to church? who will convert worldlings? who will be able to urge sinners to virtue?' If this holds true, if all are fools with thee, who can be wise? Nor will virginity be commendable, for if all be virgins, and none marry, the human race will perish. Virtue is rare, and is not desired by many." It is therefore evident that this is a foolish alarm; thus might a man fear to draw water lest the river run dry. [*St. Thomas gives no reply to the third objection, which is sufficiently solved in the body of the article.]
Objection: 1. It seems unlawful to pass from one religious order to another, even a stricter one. For the Apostle says (He 10,25): "Not forsaking our assembly, as some are accustomed"; and a gloss observes: "Those namely who yield through fear of persecution, or who presuming on themselves withdraw from the company of sinners or of the imperfect, that they may appear to be righteous." Now those who pass from one religious order to another more perfect one would seem to do this. Therefore this is seemingly unlawful.
2. Further, the profession of monks is stricter than that of canons regular (Extra, De Statu Monach. et Canonic. Reg., cap. Quod Dei timorem). But it is unlawful for anyone to pass from the state of canon regular to the monastic state. For it is said in the Decretals (XIX, qu. iii, can. Mandamus): "We ordain and without any exception forbid any professed canon regular to become a monk, unless (which God forbid) he have fallen into public sin." Therefore it would seem unlawful for anyone to pass from one religious order to another of higher rank.
3. Further, a person is bound to fulfil what he has vowed, as long as he is able lawfully to do so; thus if a man has vowed to observe continence, he is bound, even after contracting marriage by words in the present tense, to fulfil his vow so long as the marriage is not consummated, because he can fulfil the vow by entering religion. Therefore if a person may lawfully pass from one religious order to another, he will be bound to do so if he vowed it previously while in the world. But this would seem objectionable, since in many cases it might give rise to scandal. Therefore a religious may not pass from one religious order to another stricter one.
On the contrary It is said in the Decretals (XX, qu. iv, can. Virgines): "If sacred virgins design for the good of their soul to pass to another monastery on account of a stricter life, and decide to remain there, the holy synod allows them to do so": and the same would seem to apply to any religious. Therefore one may lawfully pass from one religious order to another.
I answer that It is not commendable to pass from one religious order to another: both because this frequently gives scandal to those who remain; and because, other things being equal, it is easier to make progress in a religious order to which one is accustomed than in one to which one is not habituated. Hence in the Conferences of the Fathers (Coll. xiv, 5) Abbot Nesteros says: "It is best for each one that he should, according to the resolve he has made, hasten with the greatest zeal and care to reach the perfection of the work he has undertaken, and nowise forsake the profession he has chosen." And further on he adds (cap. 6) by way of reason: "For it is impossible that one and the same man should excel in all the virtues at once, since if he endeavor to practice them equally, he will of necessity, while trying to attain them all, end in acquiring none of them perfectly": because the various religious orders excel in respect of various works of virtue.Nevertheless one may commendably pass from one religious order to another for three reasons. First, through zeal for a more perfect religious life, which excellence depends, as stated above (Question , Article ), not merely on severity, but chiefly on the end to which a religious order is directed, and secondarily on the discretion whereby the observances are proportionate to the due end. Secondly, on account of a religious order falling away from the perfection it ought to have: for instance, if in a more severe religious order, the religious begin to live less strictly, it is commendable for one to pass even to a less severe religious order if the observance is better. Hence in the Conferences of the Fathers (Coll. xix, 3,5,6) Abbot John says of himself that he had passed from the solitary life, in which he was professed, to a less severe life, namely of those who lived in community, because the hermetical life had fallen into decline and laxity. Thirdly, on account of sickness or weakness, the result of which sometimes is that one is unable to keep the ordinances of a more severe religious order, though able to observe those of a less strict religion.There is, however, a difference in these three cases. For in the first case one ought, on account of humility, to seek permission: yet this cannot be denied, provided it be certain that this other religion is more severe. "And if there be a probable doubt about this, one should ask one's superior to decide" (Extra, De Regular. et Transeunt. ad Relig., cap. Licet.). In like manner the superior's decision should be sought in the second case. In the third case it is also necessary to have a dispensation.
Reply to Objection: 1. Those who pass to a stricter religious order, do so not out of presumption that they may appear righteous, but out of devotion, that they may become more righteous.
2. Religious orders whether of monks or of canons regular are destined to the works of the contemplative life. Chief among these are those which are performed in the divine mysteries, and these are the direct object of the orders of canons regular, the members of which are essentially religious clerics. On the other hand, monastic religious are not essentially clerics, according to the Decretals (XVI, qu. i, cap. Alia causa). Hence although monastic orders are more severe, it would be lawful, supposing the members to be lay monks, to pass from the monastic order to an order of canons regular, according to the statement of Jerome (Ep. cxxv, ad Rustic. Monach.): "So live in the monastery as to deserve to become a cleric"; but not conversely, as expressed in the Decretal quoted (XIX, qu. iii). If, however, the monks be clerics devoting themselves to the sacred ministry, they have this in common with canons regular coupled with greater severity, and consequently it will be lawful to pass from an order of canons regular to a monastic order, provided withal that one seek the superior's permission (XIX, qu. iii; cap. Statuimus).
3. The solemn vow whereby a person is bound to a less strict order, is more binding than the simple vow whereby a person is bound to a stricter order. For if after taking a simple vow a person were to be married, his marriage would not be invalid, as it would be after his taking a solemn vow. Consequently a person who is professed in a less severe order is not bound to fulfil a simple vow he has taken on entering a more severe order.
Summa Th. II-II EN Qu.189 a.2