I answer that, According to Hugh (De Sacram. ii), "the sacraments, by virtue of their sanctification, contain an invisible grace." Now this sanctification is sometimes essential to the sacrament both as regards the matter and as regards the minister, as may be seen in Confirmation, and then the sacramental virtue is in both together. Sometimes, however, the essence of the sacrament requires only sanctification of the matter, as in Baptism, which has no fixed minister on whom it depends necessarily, and then the whole virtue of the sacrament is in the matter. Again, sometimes the essence of the sacrament requires the consecration or sanctification of the minister without any sanctification of the matter, and then the entire sacramental virtue is in the minister, as in Penance. Hence the power of the keys which is in the priest, stands in the same relation to the effect of Penance, as the virtue in the baptismal water does to the effect of Baptism. Now Baptism and the sacrament of Penance agree somewhat in their effect, since each is directly ordained against guilt, which is not the case in the other sacraments: yet they differ in this, that the sacrament of Penance, since the acts of the recipient are as its matter, cannot be given save to adults, who need to be disposed for the reception of the sacramental effect; whereas Baptism is given, sometimes to adults, sometimes to children and others who lack the use of reason, so that by Baptism children receive grace and remission of sin without any previous disposition, while adults do not, for they require to be disposed by the removal of insincerity. This disposition sometimes precedes their Baptism by priority of time, being sufficient for the reception of grace, before they are actually baptized, but not before they have come to the knowledge of the truth and have conceived the desire for Baptism. At other times this disposition does not precede the reception of Baptism by a priority of time, but is simultaneous with it, and then the grace of the remission of guilt is bestowed through the reception of Baptism. On the other hand, grace is never given through the sacrament of Penance unless the recipient be disposed either simultaneously or before. Hence the power of the keys operates unto the remission of guilt, either through being desired or through being actually exercised, even as the waters of Baptism. But just as Baptism acts, not as a principal agent but as an instrument, and does not go so far as to cause the reception itself of grace, even instrumentally [*See note at beginning of this article], but merely disposes the recipient to the grace whereby his guilt is remitted, so is it with the power of the keys. Wherefore God alone directly remits guilt, and Baptism acts through His power instrumentally, as an inanimate instrument, and the priest as an animate instrument, such as a servant is, according to the Philosopher (Ethic. viii, 11): and consequently the priest acts as a minister. Hence it is clear that the power of the keys is ordained, in a manner, to the remission of guilt, not as causing that remission, but as disposing thereto. Consequently if a man, before receiving absolution, were not perfectly disposed for the reception of grace, he would receive grace at the very time of sacramental confession and absolution, provided he offered no obstacle. For if the key were in no way ordained to the remission of guilt, but only to the remission of punishment, as some hold, it would not be necessary to have a desire of receiving the effect of the keys in order to have one's sins forgiven, just as it is not necessary to have a desire of receiving the other sacraments which are ordained, not to the remission of guilt, but against punishment. But this enables us to see that it is not ordained unto the remission of guilt, because the use of the keys, in order to be effective, always requires a disposition on the part of the recipient of the sacrament. And the same would apply to Baptism, were it never given save to adults.