The Collect (commonly referred to as the "opening prayer") of the Mass of Christmas during the day sounded familiar to me. The English translation I heard had to do with God wonderfully creating man and then even more wonderfully restoring him in Christ, and asking that as Jesus shared our weakness, so too we might share His glory. While the translation could have been better (and is elsewhere during the Mass!) it caused me to recollect another prayer. But first, the Latin text of the Collect:
Deus, qui humanae substantiae dignitatemThis is very similar to the prayer over the water and wine during the Offertory in the Extraordinary Form of the Roman Rite, some of which (the bolded part) is retained in the Ordinary Form:
et mirabiliter condidisti, et mirabilius reformasti,
da, quaesumus, nobis eius divinitatis esse consortes,
qui humanitatis nostrae fieri dignatus est particeps.
Deus, qui humánæ substántiæ dignitátemThe prayer is about how God wonderfully created man and even more wonderfully restored him (in Christ), and how the mingling of the water in the wine represents Christ sharing our humanity as a pledge that we will share His divinity. St. Peter wrote about that! The latter half of this Collect was translated better (not having to do with "weakness" and "glory" but, accurately, with "humanity" and "divinity") during the Offertory: "By the mystery of this water and wine, may we come to share in the divinity of Christ, who humbled himself to share in our humanity."
mirabíliter condidísti et mirabílius reformásti:
da nobis, per hujus aquæ et vini mystérium,
ejus divinitátis esse consórtes,
qui humanitátis nostræ fíeri dignátus est párticeps,
Jesus Christus, Fílius tuus, Dóminus noster:
Qui tecum vivit et regnat in unitáte Spíritus Sancti Deus:
per ómnia sæcula sæculórum. Amen.
As for the mingling of water and wine, the inimitable Fr. Z offers this commentary:
The Christmas Collect was adapted for the preparation of the chalice by the priest during every Mass. Before the priest raises the chalice upwards in offering, he mingles with the wine a very small quantity of water, just drops. The mingling of water and wine underscores three things.
First, it reveals how the Divine Son humbly accepted human nature.
Second, it shows how we will be transformed by Him in the life to come. Indeed, we who are baptized into Christ and who receive the Eucharist are already being transformed, like drops of water in His wine. In the mingling of the water and wine, the water loses itself, becoming what the wine is (though in God’s transforming embrace we do not "lose" ourselves, but rather find ourselves more perfectly!). "O admirabile commercium! O marvelous exchange!" as the Church sings at Vespers and Lauds on Christmas Octave. As Fathers of the Church expressed it the Son of God became the Son of Man so that we might become the sons of God. This "holy exchange" is the heart of Holy Mass. Bread and wine are given to us by God and we, in turn, collect them, work them, give them back to God who transforms them through the power of the Holy Spirit into the Real Presence of Christ (Body, Blood, soul and divinity). In turn the species of the Eucharist transform us, making us also into acceptable offerings to God. In this marvelous exchange earthly and temporal things mysteriously, sacramentally, become vehicles of the eternal.
Third, the mixing of those few (human) drops into the (divine) wine in the chalice (an image of sacrifice and oblation) reveals how lay people must unite their prayers and sacrifices to what the priest offers at the altar: "Pray brethren that my sacrifice and yours be acceptable to God the almighty Father." There is a distinction made regarding the way in which the priest and the people offer their sacrifices. The people offer good and acceptable sacrifice to God from their "baptismal priesthood", as members of Christ, who is High Priest. But the priest makes a very different kind of sacrifice, as alter Christus… another Christ. So, the people at Mass must unite their good offerings to those of the priest. The mingling of the water and wine is a good moment to make a conscious effort to do precisely that.