Here is the Collect for 19 December in the 2002MR, duing this period of intense preparation before Christmas:
Deus, qui splendorem gloriae tuae
per sacrae Virginis partum mundo dignatus es revelare,
tribue, quaesumus, ut tantae incarnationis mysterium
et fidei integratate colamus,
et devotio semper obsequio frequentemus.
This is from Rotulus 2 published together with the Veronese Sacramentary. It is not in any previous edition of the Missale Romanum.
The vocabulary is loaded here. First, remember that mysterium is interchangable with sacramentum, and it stands not only for our salvation, but also the celebration of Holy Mass, the Eucharist. Frequento is used to describe the participation of Christians in the sacred mysteries.
O God, who deigned to reveal to the world the splendor of Your glory,
through the holy Virgin’s giving birth,
grant, we entreat You, that we both may reverence the mystery of the great incarnation
with integrity of faith,
and we may attend it always with obedient devotion.
O God, who in the Offspring of the holy Virgin
graciously revealed to the world
the radiance of your glory,
grant, we pray,
that we may cherish with sound faith
and always celebrate with due reverence
the mystery of so wondrous an incarnation.
Do any of you have your own version?