The new translation improves upon the old one, which had inverted the first half of the prayer (switching the words of the priest with the words of the congregation) and duplicated the phrase “Lord, have mercy.” That duplication disrupted the prayer's intended antiphonal style and made this form of the Penitential Act appear to be just an abbreviated version of Form C of the Penitential Act (which incorporates the Kyrie, eleison — "Lord, have mercy").
The dialogue begins:
Priest: Have mercy on us, O Lord.Bar 3:2aThis profession of guilt reminds us of our need to live holy lives “worthy of the calling to which [we] have been called.” (Eph 4:1) The plea for mercy reminds us of how ready God is to bestow the abundance of His gracious mercy upon us.
Congregation: For we have sinned against you.Bar 3:2b
P: Show us, O Lord, your mercy.Ps 85:7aWe do not simply ask the Lord for mercy, but for His salvation. The Lord Jesus did not come to earth simply to forgive our sins, but to “bring us to everlasting life,” as the priest says in the prayer at the end of the Penitential Act. Through Jesus Christ, we have not only the forgiveness of our sins, but the hope of eternal salvation.
C: And grant us your salvation.Ps 85:7b
Dom Prosper Guéranger, a nineteenth century Benedictine priest and liturgical scholar, interpreted this verse (and its context, Psalm 85) in a Christological way. This psalm of David begins by recalling God's past mercy to Israel; then it asks God to be merciful still. Guéranger saw in the request for God to show "mercy" and to grant "salvation" prophetic language which longs for the appearance of the Messiah, the Christ. The remainder of the psalm continues this Christological language: "Faithfulness will spring up from the ground, and righteousness will look down from the sky." (Ps 85:11) This language is similar to that found in Isaiah 45:8, a verse interpreted in the Church as a prophecy of the Incarnation and used in the Advent chant Rorate caeli ("Drop down dew, O heavens").
Guéranger’s point should remind us, as we look at the rest of the prayers of the Mass, that to understand the words of the prayers that come from Scripture, we need to look at their context in Scripture. So where do the words from Baruch fit in?
Baruch 1:15–3:8 is one long prayer of contrition to the Lord: it expresses the righteousness of the Lord in contrast to the unfaithfulness of Israel to their covenant with God, which led to their exile. Much like the Confiteor includes a threefold admission of guilt – “through my fault, through my fault, through my most grievous fault” – so in the prayer of Baruch we read “we have sinned, we have been ungodly, we have done wrong, O Lord our God, against all your ordinances.” (Bar 2:12) The prayer goes on to recognize that the Israelites were moved to contrition by God Who, in His compassion, gave them “a heart that obeys and ears that hear.” (Bar 2:31)
As these words from Baruch are spoken at Mass, let us remember that we who are God's people are still sinners in need of forgiveness every day. We must live “worthy of the calling to which [we] have been called” (Eph 4:1), and when we fail to do so, we must turn to the Lord with contrite hearts and seek His mercy. His mercy has been manifested in the flesh: His Son, Jesus Christ, Who is our salvation.