Let’s see the Collect for the Third Mass of Christmas, the Mass “during the day”, in the Ordinary Form or Novus Ordo. It may be the most audacious prayer in the whole Missal: Deus, qui humanae substantiae dignitatem et mirabiliter condidisti, et mirabilius reformasti, da, quaesumus, nobis eius divinitatis esse consortes, qui humanitatis nostrae fieri dignatus est particeps.
Literal translation: O God, who in a wondrous way created the dignity of human nature, and shaped it anew yet more wondrously, grant us, we beg, to be partakers of the Godhead of Him who deigned to become a participant of our humanity.
Current ICEL translation: O God, who wonderfully created the dignity of human nature and still more wonderfully restored it, grant, we pray, that we may partake in the divinity of him who humbled himself to share in our humanity.
Note the “divinisation” of man. God the Son stooped infinitely below Himself in His kénosis, His self-emptying, to take our flesh and a human soul and become a man, like us in all ways except in sin. Our human nature is now, through the indestructible bond with Christ’s divinity, the “admirabile commercium … wondrous exchange”, elevated to an even greater dignity than we had before the Fall.
At Christmas we adore Jesus in his sweet and vulnerable humility. The Eternal Word became a speechless Child, as St Augustine preached. During every Mass we do well to ponder the mystery of the Incarnation. On Christmas in Masses with the Novus Ordo we fittingly genuflect during the Creed at the words “et homo factus est… and He became man”. We do this during every Mass with the Creed in the Extraordinary Form.
By the Middle Ages this Collect had been adapted for the blessing of the tiny amount of water to be mingled with the wine in the chalice. The mingling of water and wine symbolises that the Divine Son emptied Himself and accepted human nature without losing His divinity. It also shows that our humanity will be transformed in the life to come. The water loses itself, becoming what the wine is. “O admirabile commercium!”
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. We who are baptised into Christ and who receive the Eucharist are already being transformed, like drops of water in His wine.