This is my favorite Gregorian chant;
"
Puer natus est nobis is the introit for the Mass of Christmas Day and, in the Extraordinary Form, its Octave. It is drawn from Isaiah 9:6; the verse is from Psalm 98 (97) and the antiphon is repeated after the Gloria Patri."
Puer Natus Est Nobis (Christmas Day, Introit)
Puer natus est nobis
Et filius datus est nobis
Cuius imperium super humerum eius
Et vocabitur nomen eius
Magni consilii Angelus
Cantate Domino canticum novum
Quia mirabilia fecit
Gloria Patri, et Filio, et Spiritui Sancto
Sicut erat in principio, et nunc, et semper,
in secula seculorum. Amen.
(In English)
A boy is born to us,
And a son is given to us,
upon whose shoulders authority rests,
and His name will be called
"The Angel of Great Counsel".
Sing to the Lord a new song,
because he has done the miraculous.
Glory to the Father, and to the Son, and to the Holy Spirit.
As it was in the beginning, and is now, and always will be,
in every human generation. Amen.