Objection 1. It would seem that it is possible to be dispensed from a solemn vow of continency. As stated above, one reason for granting a dispensation from a vow is if it be an obstacle to a greater good. But a vow of continency, even though it be solemn, may be an obstacle to a greater good, since the common good is more God-like than the good of an individual. Now one man's continency may be an obstacle to the good of the whole community, for instance, in the case where, if certain persons who have vowed continency were to marry, the peace of their country might be procured. Therefore it seems that it is possible to be dispensed even from a solemn vow of continency.
Objection 2. Further, religion is a more excellent virtue than chastity. Now if a man vows an act of religion, e.g. to offer sacrifice to God he can be dispensed from that vow. Much more, therefore, can he be dispensed from the vow of continency which is about an act of chastity.
Objection 3. Further, just as the observance of a vow of abstinence may be a source of danger to the person, so too may be the observance of a vow of continency. Now one who takes a vow of abstinence can be dispensed from that vow if it prove a source of danger to his body. Therefore for the same reason one may be dispensed from a vow of continency.
Objection 4. Further, just as the vow of continency is part of the religious profession, whereby the vow is solemnized, so also are the vows of poverty and obedience. But it is possible to be dispensed from the vows of poverty and obedience, as in the case of those who are appointed bishops after making profession. Therefore it seems that it is possible to be dispensed from a solemn vow of continency.
On the contrary, It is written (Sirach 26:20): "No price is worthy of a continent soul."
Further, (Extra, De Statu Monach.) at the end of the Decretal, Cum ad Monasterium it is stated that the "renouncing of property, like the keeping of chastity, is so bound up with the monastic rule, that not even the Sovereign Pontiff can disperse from its observance."
I answer that, Three things may be considered in a solemn vow of continency: first, the matter of the vow, namely, continency; secondly, the perpetuity of the vow, namely, when a person binds himself by vow to the perpetual observance of chastity: thirdly, the solemnity of the vow. Accordingly, some [William of Auxerre, Sum. Aur. III. vii. 1, qu. 5 say that the solemn vow cannot be a matter of dispensation, on account of the continency itself for which no worthy price can be found, as is stated by the authority quoted above. The reason for this is assigned by some to the fact that by continency man overcomes a foe within himself, or to the fact that by continency man is perfectly conformed to Christ in respect of purity of both body and soul. But this reason does not seem to be cogent since the goods of the soul, such as contemplation and prayer, far surpass the goods of the body and still more conform us to God, and yet one may be dispensed from a vow of prayer or contemplation. Therefore, continency itself absolutely considered seems no reason why the solemn vow thereof cannot be a matter of dispensation; especially seeing that the Apostle (1 Corinthians 7:34) exhorts us to be continent on account of contemplation, when he says that the unmarried woman... "thinketh on the things of God [Vulgate: 'the Lord']," and since the end is of more account than the means.
Consequently others [Albertus Magnus, Sent. iv, D, 38 find the reason for this in the perpetuity and universality of this vow. For they assert that the vow of continency cannot be canceled, save by something altogether contrary thereto, which is never lawful in any vow. But this is evidently false, because just as the practice of carnal intercourse is contrary to continency, so is eating flesh or drinking wine contrary to abstinence from such things, and yet these latter vows may be a matter for dispensation.
For this reason others [Innocent IV, on the above decretal] maintain that one may be dispensed even from a solemn vow of continency, for the sake of some common good or common need, as in the case of the example given above (Objection 1), of a country being restored to peace through a certain marriage to be contracted. Yet since the Decretal quoted says explicitly that "not even the Sovereign Pontiff can dispense a monk from keeping chastity," it follows seemingly, that we must maintain that, as stated above (10, ad 1; cf. Leviticus 27:9-28), whatsoever has once been sanctified to the Lord cannot be put to any other use. For no ecclesiastical prelate can make that which is sanctified to lose its consecration, not even though it be something inanimate, for instance a consecrated chalice to be not consecrated, so long as it remains entire. Much less, therefore, can a prelate make a man that is consecrated to God cease to be consecrated, so long as he lives. Now the solemnity of a vow consists in a kind of consecration or blessing of the person who takes the vow, as stated above (Article 7). Hence no prelate of the Church can make a man, who has pronounced a solemn vow, to be quit of that to which he was consecrated, e.g. one who is a priest, to be a priest no more, although a prelate may, for some particular reason, inhibit him from exercising his order. On like manner the Pope cannot make a man who has made his religious profession cease to be a religious, although certain jurists have ignorantly held the contrary.
We must therefore consider whether continency is essentially bound up with the purpose for which the vow is solemnized. because if not, the solemnity of the consecration can remain without the obligation of continency, but not if continency is essentially bound up with that for which the vow is solemnized. Now the obligation of observing continency is connected with Holy Orders, not essentially but by the institution of the Church; wherefore it seems that the Church can grant a dispensation from the vow of continency solemnized by the reception of Holy Orders. on the other hand the obligation of observing; continency is an essential condition of the religious state, whereby a man renounces the world and binds himself wholly to God's service, for this is incompatible with matrimony, in which state a man is under the obligation of taking to himself a wife, of begetting children, of looking after his household, and of procuring whatever is necessary for these purposes. Wherefore the Apostle says (1 Corinthians 7:33) that "he that is with a wife, is solicitous for the things of the world, how he may please his wife; and he is divided." Hence the "monk" takes his name from "unity" [The Greek monos] in contrast with this division. For this reason the Church cannot dispense from a vow solemnized by the religious profession; and the reason assigned by the Decretal is because "chastity is bound up with the monastic rule."
Reply to Objection 1. Perils occasioned by human affairs should be obviated by human means, not by turning divine things to a human use. Now a professed religious is dead to the world and lives to God, and so he must not be called back to the human life on the pretext of any human contingency.
Reply to Objection 2. A vow of temporal continency can be a matter of dispensation, as also a vow of temporal prayer or of temporal abstinence.
But the fact that no dispensation can be granted from a vow of continency solemnized by profession is due, not to its being an act of chastity, but because through the religious profession it is already an act of religion.
Reply to Objection 3. Food is directly ordered to the upkeep of the person, therefore abstinence from food may be a direct source of danger to the person: and so on this count a vow of abstinence is a matter of dispensation. On the other hand sexual intercourse is directly ordered to the upkeep not of the person but of the species, wherefore to abstain from such intercourse by continency does not endanger the person. And if indeed accidentally it prove a source of danger to the person, this danger may be obviated by some other means, for instance by abstinence, or other corporal remedies.
Reply to Objection 4. A religious who is made a bishop is no more absolved from his vow of poverty than from his vow of continency, since he must have nothing of his own and must hold himself as being the dispenser of the common goods of the Church. On like manner neither is he dispensed from his vow of obedience; it is an accident that he is not bound to obey if he have no superior; just as the abbot of a monastery, who nevertheless is not dispensed from his vow of obedience.
The passage of Ecclesiasticus, which is put forward in the contrary sense, should be taken as meaning that neither fruitfulness of the of the flesh nor any bodily good is to be compared with continency, which is reckoned one of the goods of the soul, as Augustine declares (De Sanct. Virg. viii). Wherefore it is said pointedly "of a continent soul," not "of a continent body."
Source: Summa Theologica (New Advent)