The Great Mystery is a nice bit of Literny from the Roman Catholic Tradition, often used as an Antiphone
O magnum mysterium,
et admirabile sacramentum,
ut animalia viderent Dominum natum,
jacentem in praesepio!
Beata Virgo, cujus viscera
O great mystery,
and wonderful sacrament,
that animals should see the new-born Lord,
lying in a manger!
Blessed is the Virgin whose womb
was worthy to bear
Christ the Lord.
Another Carol from Russia, which was turned into a carillion on bells
...and finally for now I leave you with the etherial Golden Light (Lux Aurumque)
calida gravisque pura velut aurum
et canunt angeli molliter
warm and heavy as pure gold
and the angels sing softly
to the new-born baby