The liturgy would begin with the choir singing the Introit. But not the one you might expect. It's Rorate Coeli's introit (we think of as the 4th Sunday of Advent). And it's sung in Latin. Probably along these lines:
For some unknown reason, the Ad Te Levavi propers have wandered over to Tuesday of Advent I. When the choir completed the Introit, a three-fold (rather than traditional nine-fold) Kyrie was intoned and the Gloria in Excelsis was sung - in Latin.
A German collect would follow along these lines. Let us pray. Dear Lord God, stir us up that we be prepared when Your Son comes to welcome Him with joy and to serve You with pure hearts; through Jesus Christ, our Lord. [Note that this prayer is used throughout the season]
The Epistle is read (that is, chanted): Romans 13:11 through the end of the chapter.
The Alleluia was also in Latin - you can hear it here. Also from the Fourth Sunday for some reason.
The Alleluia is immediately followed by the Sequence: "Mittit ad Virgine." This also in Latin. Here is an English translation:
The lover of mankind sent to the Virgin
not just any angel, but his strength, his
archangel. May that angel declare for
us the mighty message, that he may
effect on nature God's foreordination of
birth to a virgin.
overcome nature, let him reign and rule
and remove from our midst the weight
of the dross. Let him who is mighty in
battle frighten the proud on their
heights, treading in his might upon their
Let him oust the worldly prince, and
make his mother a partner with him in
his Father's kingdom. Go forth, you
who spread these gifts, unveil the
ancient writings by the strength of your
Give your tidings in person; say "Hail",
say "full of grace", say, "the Lord is
with you", and say "Fear not." O virgin
may you take up what God has entrusted
to you; thereby may you accomplish
your chaste intention and may you keep
The maiden hears and accepts the
message; she believes and conceives
and bears a son, a wondrous one: the
counselor of the human race, and the
God of the strong, and father to future
generations, one firm in peace [rather than faith].
That He may give to us sinners remission of sins,
defense against guilt,
And a homeland in highest heaven.
I should note that the Latin was altered a bit at the end. It originally concluded:
Whose firmness makes us firm, lest our
earthly wandering impede us from being
sharers with him. May the granter of
pardon, in His superabundant mercy,
once we have obtained grace through
the Mother of Glory, dwell in us.
A most Lutheran adaptation there at the end, letting the chief thing be the chief thing.
You can hear the Latin sequence, not emended, here.
The Gospel, Matthew 21:1-10 was then chanted. This was followed by the Creed, first sung entirely in Latin and then followed by the "German Symbol" - that is, Luther's paraphrase such as you can hear here.
Then the "Concio" - the sermon commenced. When the preaching was finished, the congregation joined in Luther's Te Deum: "Herr Gott, Dich Loben Wir."
We know from another work (two years from the publication of this one) that the elements would be processed to the altar as choir boys sang: "Grant Peace, We Pray" and accompanied by incense.
The Preface followed, but with a twist at the Proper Preface. Here we read, still in Latin: "who on this day comes to us still as the meek Savior through the pure preaching of the Gospel and the right administration of the Sacraments in this purified temple. Therefore with angels..."
The Sanctus is in Latin - tone IV from the Liber, I believe. This is followed by the minister singing the Lord's Prayer and the Words of Institution of the Supper. Afterwards, as the congregation communes, the Choir sings either "Jesus Christ, Our Blessed Savior" or the Latin or German Agnus Dei.
The distribution concluded, the final collect (from Luther's 1526 German Mass) is chanted in German and the people are blessed with the Aaronic benediction, also in German. The Mass concludes with the Choir singing the German "O Lord, We Praise Thee."
So a MASSIVE load of Latin up front; a switch to German for the readings, for the sermon, and for post-Sanctus liturgy, perhaps excepting the Agnus. Would love to have the whole thing recorded as the Praetorius Mass for Christmas Day was - from roughly about the same time.