100 This we are also taught by those exhortations which the Bishop, in the Church's name, addresses to priests on the day of their ordination, "Understand what you do, imitate what you handle, and since you celebrate the mystery of the Lord's death, take good care to mortify your members with their vices and concupiscences." In almost the same manner the sacred books of the liturgy advise Christians who come to Mass to participate in the sacrifice: "At this . . . altar let innocence be in honor, let pride be sacrificed, anger slain, impurity and every evil desire laid low, let the sacrifice of chastity be offered in place of doves and instead of the young pigeons the sacrifice of innocence." While we stand before the altar, then, it is our duty so to transform our hearts, that every trace of sin may be completely blotted out, while whatever promotes supernatural life through Christ may be zealously fostered and strengthened even to the extent that, in union with the immaculate Victim, we become a victim acceptable to the eternal Father.
Source: Mediator Dei (Vatican.va)