Whether the forgiveness of guilt is an effect of Penance?

Objections

Objection 1 : It would seem that the forgiveness of guilt is not an effect of penance as a virtue. For penance is said to be a virtue, in so far as it is a principle of a human action. But human action does nothing towards the remission of guilt, since this is an effect of operating grace. Therefore the forgiveness of guilt is not an effect of penance as a virtue.
Objection 2 : Further, certain other virtues are more excellent than penance. But the forgiveness of sin is not said to be the effect of any other virtue. Neither, therefore, is it the effect of penance as a virtue.
Objection 3 : Further, there is no forgiveness of sin except through the power of Christ's Passion, according to Heb. 9:22: "Without shedding of blood there is no remission." Now Penance, as a sacrament, produces its effect through the power of Christ's Passion, even as the other sacraments do, as was shown above (Question [62], Articles [4],5). Therefore the forgiveness of sin is the effect of Penance, not as a virtue, but as a sacrament.