I suppose we are now in such a state of affairs that we need to have grammar explained. That was certainly the case when the Congregation for Divine Worship, in a response to a dubium, had to explain the Latin of GIRM 299. And yet the USCCB’s writers still got the Latin wrong.
From the USCCB’s Committee on Divine Worship’s newsletter:
Understanding the Grammar of the Roman Missal, Third Edition
As English–speaking Catholics in the United States become more familiar— and more comfortable— with the Roman Missal, Third Edition, there are sometimes questions that arise, especially as we progress through the liturgical seasons and the Sanctoral cycle (the Proper of Saints), encountering new texts for the first time. Many have questioned particular elements that are commonly found in the Roman Missal but were not present in the earlier translation in the Sacramentary. [Such as... accuracy, doctrine, lack of Pelagian tendencies, the cessation of banality...] The Secretariat for Divine Worship offers commentary on two frequently-raised issues: [This is a little embarrassing...] the qui clauses (relative or dependent clauses beginning with the relative pronoun “who”), which are found not only in the proper orations of the Missal but also in the Order of Mass, and the expression quaesumus (usually translated as “we pray”).
The complex grammatical structure of the orations was one of the major changes in the style of English used in the new translation of the Missal. [As opposed to the parataxis imposed on the prayers, which made the internal logic of the original less than apparent.] The use of relative or dependent clauses, not commonly used in everyday spoken English, but certainly found in written communication, necessitates practice for effective proclamation. In these clauses, it is useful to point out that in direct address, “who” functions as “you.” [Ah the fruits of the destruction of actual education for the last few decades!] During the preparation of the original draft translations by the International Commission on English in the Liturgy, it was determined that the grammatical construction of the qui clause was to be maintained in English, in order to avoid the awkwardness of a rendering that gave the appearance of telling God what God already knows. ["O God, you are so big!"] The rendering of the relative clause, however, allows oration to begin with a description of God’s power and action tied to the address, i.e., we can call on God by name because of what God has already revealed and accomplished. This is the case, for example, in the Collect for the Second Sunday in Ordinary Time:
Almighty ever–living God,
who govern all things, [qui caelestia simul et terrena moderaris]
both in heaven and on earth,
mercifully hear [exaudi (an imperative)] the pleading of your people
and bestow your peace on our times.
[Dear reader, we, clerics especially, should know this stuff already as part of the decent education denied to them from childhood.] The verb “govern” agrees with “who” (acting in the place of “you,” 2nd person, singular, in the relative clause). “[G]overns,” on the other hand, is 3rd person singular, and to use that form would transform the first part of the prayer to indirect address, i.e., speaking about God rather than speaking to God. As it is, the verb in the relative clause (“govern”) must agree with the verb in the main clause (“hear” and “bestow”). This grammatical form is found also in the Communion Rite in the Order of Mass, in the concluding formula of prayer before the Sign of Peace: “Who live and reign for ever and ever.” Because this prayer is addressed to Christ, the concluding formula takes on the form of direct address, and is therefore in the 2nd person singular. To do otherwise, i.e., “Who lives and reigns,” would shift the conclusion from direct to indirect address, 3rd person singular, and it would not agree with the rest of the prayer. [Okay... I will admit that people fall into the trap with these qui clauses in the second person, turning them into the third.]
While some have observed that the use of the relative or dependent clause is not frequently heard in contemporary American English, it is not altogether foreign. [sigh] It is used, albeit in an archaic form of English, in the opening line of the Lord’s Prayer: “Our Father, who art in heaven…” In this case, “art” is an archaic form of “are,” as though we were saying “Our Father, you who are in heaven…” [sigh]
Another commonly used expression in the orations of the Missal is the phrase “we pray” as a translation of quaesumus, sometimes rendered otherwise as “we ask” or “we beg.” [I like "beseech".] It is found, for example, in the Prayer after Communion for the Fourteenth Sunday in Ordinary Time:
Grant, [an imperative in English] we pray, [praesta, quaesumus] O Lord,
that, having been replenished by such great gifts,
we may gain the prize of salvation
and never cease to praise you.
This expression helps communicate a sense of humility, or at least a sense of politeness, before God. [I would rather say a "courtly" attitude. This is decorum. Language that is apt for worship much involve decorum.] In the Lord’s Prayer our petitions are expressed boldly, in the imperative, because that is the way Jesus taught us to pray. The verb form in the orations, however, is not the imperative [EHEM... praesta is the main verb and it is, in this prayer, an imperative. The prayer is, basically, "Grant X" while the "we ask you" is a parenthesis.] but a combination of the indicative and the subjunctive, [Is that so?] because when we pray of our own volition we are not always so bold. [I hope that the writer knows that the main verb is the imperative. But I sense that the writer is trying to do a backflip to distract us from any notion that our prayers are bossy. That is to focus on only one range of the meaning of an imperative. On the contrary, an imperative verb need not be automatically "bossy". There is a "bossy" imperative" and a "trusting" imperative, as it were. It can have the force of a heartfelt wish, or as Messers Guildersleeve and Lodge say, "The Imperative is the mood of the will. It wills that the predicate be made a reality. The tone of the Imperative varies from stern command to piteous entreaty. It may appear as a demand, an order, an exhortation, a permission, a concession, a prayer."] We stand humbly before God and plead for his mercy and kindness. [Imperatives don't make us less humble.] This expression and sentiment is not new to the Roman Missal, Third Edition. In the earlier translation found in the Sacramentary, the expression was included in every prayer, whether or not the Latin expression quaesumus was present, in the concluding formula, “We ask this through Christ our Lord.”
We might look more closely at the Post Communion of the 14th Sunday. It has roots in the Gelasian Sacramentary. In the 1962 Missale Romanum it was the Postcommunio of 1st Sunday after Pentecost (Trinity Sunday) used during the weekdays that follow Trinity Sunday.
POST COMMUNIONEM (2002MR):
Tantis, Domine, repleti muneribus,
praesta, quaesumus, ut et salutaria dona capiamus,
et a tua numquam laude cessemus.
The astounding Lewis & Short Dictionary helps with cesso, which means “to stand back very much; hence, to be remiss in any thing, to delay, loiter, or, in general, to cease from, stop, give over”. You might be familiar with the Latin proverbial saying “Ubi maior, minor cessat… Where the greater thing is, the lesser gives way”. For example, when the sun shines during the daylight hours the stars, otherwise visible at night, give way and are no longer to be seen. Capio ranges in meaning but is basically, “to take in hand, take hold of, lay hold of, take, seize, grasp”.
OBSOLETE ICEL (1973):
may we never fail to praise you
for the fullness of life and salvation
you give us in this eucharist.
Having been filled, O Lord, with such great gifts,
grant, we beg You, that we may both grasp the saving gifts
and also never cease from Your praise.
This is a tricky prayer to put into smooth English. First, we run the risk of repetition by saying “gifts” (munera) and “gifts” (dona) in such close proximity. Also, numquam cessare a laude tua clearly means “never cease/quit praising you” while “cease from your praise” is awkward. Moreover, capio with its vast range of meanings is a deep enough word that a single English word hardly suffices to get at what it drives at. I try to solve this by just taking capio as “grasp”, a physical concept. We can simultaneously “grasp” on to it as meaning both an intellectual “grasping” of the mysterious moment of Communion as well as a more affective “grasping” after the sole source of our salvation, the Man God Christ Jesus, truly present in the Host we just consumed moments before this prayer is uttered.
Having been filled, O Lord, with gifts so great as these,
grant, we beseech You, that we may both grasp these salvation bringing gifts,
and never cease from rendering the praise which is Your due.
At this point in Mass, we have just been given a foretaste of the heavenly life offered us by God. So great a gift, undeserved as it is, demands a response. In heaven we will never cease praising God, whom we shall see face to face. But we are not in heaven now. Holy Communion demands a response of praise here and now.