The costs of mistakes must be covered.
1 From this, then, it is evident that if a man sins after baptism, he cannot have the remedy against his sin in baptism. And since the abundance of the divine mercy and the effectiveness of Christ’s grace do not suffer him to be dismissed without a remedy, there was established another sacramental remedy by which sins are washed away.
And this is the sacrament of penance, which is spiritual healing of a sort. For just as those who receive a natural life by generation can, if they incur some disease which is contrary to the perfection of life, be cured of their disease: not, indeed, so as to be born a second time, but healed by a kind of alteration; so baptism, which is a spiritual regeneration, is not given a second time against sins committed after baptism, but they are healed by penance which is a kind of spiritual alteration.
2 Let this, however, be considered: bodily healing is at times wholly from within, as when one is cured by the power of nature alone. But there are times when one is cured from within and from without simultaneously, for example, when the operation of nature is helped by the external benefit of medicine.
But it never happens that one is cured entirely from without, for he still has within himself the principles of life, and from these the healing is somehow caused within him. But spiritual healing, it happens, cannot be brought about entirely from within, for we showed in Book III that man cannot be delivered from fault except by the help of grace. In like fashion, also, neither can his spiritual cure be entirely from an external thing; for the soundness of his mind would not be restored unless ordered movements of will were caused in man. Therefore, the spiritual health in the sacrament of penance must proceed both from something internal and from something external.
3 This comes about in this way. For a man to be perfectly cured of a bodily disease, he necessarily must be freed from all the inconveniences which the disease involves. Thus, then, even the spiritual cure of penance would not be perfected unless a man were relieved of all the damages into which he has been led by sin.
Now, the first damage which man sustains from sin is the disordering of the mind; in that man is turned away from the incommutable good—namely, God—and is turned toward sin. But the second damage is that he incurs the guilt of punishment, for, as was shown in Book III, God the most just ruler requires a punishment for every fault. The third damage is a certain weakening of the natural good, in that man by sinning is rendered more prone toward sinning and more reluctant toward doing well.
Notes The old saying is sin makes you stupid.
4 Therefore, the first thing required in penance is the ordering of the mind; namely, that the mind be turned toward God, and turned away from sin, grieving at its commission, and proposing not to commit it; and this belongs essentially to contrition.
5 But this reordering of the mind cannot be without grace, for our mind cannot duly be turned toward God without charity, but one cannot have charity without grace, as is clear from what was said in Book III. Thus, then, by contrition the offense to God is removed and one is also freed from that guilt of eternal punishment which cannot be simultaneously with grace and charity; for there is no eternal punishment except by separation from God, and by grace and charity man is united with Him. Therefore, this reordering of the mind, which consists of contrition, proceeds from within, that is, from the free will with the help of divine grace.
6 Since, however, it was established above that the merit of Christ suffering for the human race works for the expiation of all sins, if a man is to be healed of sin his mind must necessarily cleave not only to God, but also to the mediator of God and men, Jesus Christ, in whom rests the remission of all sins. For spiritual health consists in the turning of the mind to God, and, to be sure, we cannot achieve this health except through the physician of our souls, Jesus Christ, “who shall save His people from their sins” (Mat. 1:21). Indeed, His merit is sufficient to take away all sins altogether, for it is He “‘who takes away the sins of the world” as John (1:29) says. Nonetheless, not all achieve perfectly the effect of remission; each achieves it in the measure in which he is conjoined with Christ suffering for sins.
7 Our conjunction, then, with Christ in baptism is not in accord with our operation (from within, so to say), because nothing generates itself in being, but it is from Christ, who “regenerated us unto a lively hope” (1 Peter 1:3); therefore, the remission of sins in baptism is made in accord with the power of Christ conjoining us perfectly and entirely with Himself, so as not only to take away every impurity of sin, but also to free us entirely from every guilt of punishment; except incidentally, perhaps, in the case of those who do not get the effect of the sacrament because they approach with a false attitude.
8 In the later spiritual healing we are conjoined to Christ in accord with our own operation informed by divine grace. Hence, we do not always entirely, nor do we all equally, achieve the effect of remission by this conjunction. For there can be a turning of the mind toward God, and to the merit of Christ, and to the hatred of sin which is so vehement that a man perfectly achieves the remission of sin, not only with regard to wiping out the fault, but even with regard to remission of the entire punishment. But this does not always happen. Hence, after the fault is taken away by contrition and the guilt of eternal punishment is relieved (as was said), there sometimes persists an obligation to some punishment to maintain the justice of God which requires that fault be ordered by punishment.
9 Since, however, to undergo punishment for a fault calls for a kind of judgment, the penitent who has committed himself to Christ for healing must look to Christ’s judgment for fixing the punishment; and this, indeed, Christ does through His ministers, just as He does in the other sacraments. But no one can judge of faults which he does not know. It was necessary, then, that confession be instituted, the second part of this sacrament, so to say, in order to make the fault of the penitent known to the minister of Christ.
10 The minister, therefore, to whom confession is made must have judiciary power representing Christ, “who was appointed to be judge of the living and the dead” (Acts 10:42). For judiciary power two things are required: namely, the authority to know about the fault, and the power to absolve or condemn. And these two are called the “two keys of the Church,” namely, the knowledge to discern and the power to bind and loose which our Lord committed to Peter as Matthew (16:19) has it: “I will give to you the keys of the kingdom of heaven.” He is not understood to have committed these to Peter so that he alone might have them, but so that they might through him be passed on to others; otherwise, sufficient provision for the salvation of the faithful would not have been made.
11 Of course, keys of this kind have their effectiveness from the suffering of Christ by which, we know, Christ opened for us the door of the kingdom of heaven. Accordingly, just as without baptism, in which the suffering of Christ works, there cannot be salvation for men—whether the baptism be really received, or desired to the purpose “when necessity, but not contempt, excludes the sacrament”—so for those sinning after baptism there can be no salvation unless they submit themselves to the keys of the Church, whether it be by actually confessing and undergoing the judgment of the ministers of the Church, or at least having this as a purpose to be fulfilled at the opportune time; because, as Peter says: “There is no other name given to men whereby we must be saved except by the name of our Lord Jesus Christ” (Acts 4:10-12).
12 In this way one avoids the error of some who held that a man can achieve forgiveness of sins without confession and without the purpose of confessing, and that the prelates of the Church can dispense one from the obligation of confessing. For the prelates of the Church are unable “to make vain the keys of the Church” in which their entire power consists, and they cannot bring it about that one achieve the remission of his sins apart from a sacrament which has power from the passion of Christ.
This belongs only to Christ, who established the sacraments and is their author. Thus, then, as there can be no dispensation from the prelates of the Church allowing one to be saved without baptism, neither can there be one allowing a man to achieve the remission of his sins without confession and absolution.
13 Nonetheless, there is this consideration. Baptism has some effectiveness for the remission of sins even before it is actually received, while one has the purpose of receiving it. We grant that afterwards—when it is actually received—it bestows a fuller effect both in the achievement of grace and in the remission of fault.
Sometimes, too, grace is bestowed in the very reception of baptism and a fault is remitted for which previously there was no remission. And thus the keys of the Church have effectiveness in one before he actually submits himself to them, provided that he has the purpose of submitting himself to them; nevertheless, he achieves fuller grace and forgiveness when he actually submits himself to the keys by confessing and receiving absolution; and nothing prevents our thinking that sometimes a grace is conferred by the power of the keys on one who has confessed, in the course of the absolution itself, and that by this grace his fault is dismissed.
14 Therefore, since even in the very confession and absolution a fuller effect of grace and remission is bestowed on him who—by reason of his good purpose—had previously obtained both, manifestly the minister of the Church, absolving by the power of the keys, dismisses something of the temporal punishment for which the penitent remains in debt after contrition. He does, however, oblige the penitent to the balance by his command. And this fulfillment of the obligation is called satisfaction, which is the third part of penance.
By this a man is entirely freed from the guilt of punishment when he pays the penalty which he owed; further, the weakness of the natural good is cured when a man abstains from bad things and accustoms himself to good ones: by subjecting his spirit to God in prayer, or by taming his flesh by fasting to make it subject to the spirit, and in external things by uniting himself by giving alms to the neighbors from whom his fault had separated him.
15 Thus, clearly, then, the minister of the Church exercises a certain judgment in the use of the keys. But judgment is not granted to one unless it be judgment on those who are his subjects. Hence, it is manifest that it is not any priest at all who can absolve any man at all from sin—as some falsify it; he can absolve only one over whom he has received power.