This text comes from Psalm (121/)122, v. 1:
I was glad when they said to me,
“Let us go to the house of the Lord!”
Here's the full score:
This Sunday's emphasis in the chant propers is heavily on Zion / Jerusalem; other propers (sung by the Benedictines of Sao Paolo, Brazil) on the day are:
Introitus: Cf. Is. 30, 19.30; Ps. 79 Populus Sion (3m15.8s - 3061 kb) score
Graduale: Ps. 40, 2.3. V. 5 Ex Sion (2m50.7s - 2675 kb) score
Alleluia: Ps. 121, 1 Lætatus sum (2m11.2s - 2057 kb) score
Offertorium: Ps. 84, 7.8 Deus, tu convertens (2m01.6s - 1901 kb) score
Communio: Bar. 5, 5; 4, 36 Ierusalem, surge cum Ps. 147, 12.13 (1m56.7s - 1825 kb) score
As you can see, four of five of the propers concern themselves directly with Zion / Jerusalem; that is really a very insistent theme! I have been looking through various lectionaries from various periods to try to understand the Zion theme; so far I've had no luck. This page contains what it says is a "Medieval Lectionary" - and I can find no reason there for the strong emphasis on Zion/Jerusalem. (The Gospel then was apparently Luke 21:25-36 - "And there shall be signs in the sun, and in the moon, and in the stars; and upon the earth distress of nations, with perplexity; the sea and the waves roaring...." - and the Epistle is the same Romans passage we're reading now, below.)
I do plan to read more about this, though, and will post what I find. It could simply be that the Introit, Populus Sion, is setting the tone with its text from the very Advent-ish Isaiah: "People of Sion, behold the Lord shall come to save the nations: and the Lord shall make the glory of His voice to be heard, in the joy of your heart." - and that the rest of the propers follow from this theme.
The current readings for today, including today's collect, by contrast, emphasize Prophets. We are back to Year A in the Lectionary, and are looking at some of the really wonderful readings of the year - the Isaiah Advent passages in particular, and the Gospel gives us John the Baptist.
Here is that collect:
Merciful God, who sent your messengers the prophets to preach repentance and prepare the way for our salvation: Give us grace to heed their warnings and forsake our sins, that we may greet with joy the coming of Jesus Christ our Redeemer; who lives and reigns with you and the Holy Spirit, one God, now and for ever. Amen.
And the readings:
A shoot shall come out from the stump of Jesse,
and a branch shall grow out of his roots.
The spirit of the LORD shall rest on him,
the spirit of wisdom and understanding,
the spirit of counsel and might,
the spirit of knowledge and the fear of the LORD.
His delight shall be in the fear of the LORD.
He shall not judge by what his eyes see,
or decide by what his ears hear;
but with righteousness he shall judge the poor,
and decide with equity for the meek of the earth;
he shall strike the earth with the rod of his mouth,
and with the breath of his lips he shall kill the wicked.
Righteousness shall be the belt around his waist,
and faithfulness the belt around his loins.
The wolf shall live with the lamb,
the leopard shall lie down with the kid,
the calf and the lion and the fatling together,
and a little child shall lead them.
The cow and the bear shall graze,
their young shall lie down together;
and the lion shall eat straw like the ox.
The nursing child shall play over the hole of the asp,
and the weaned child shall put its hand on the adder's den.
They will not hurt or destroy
on all my holy mountain;
for the earth will be full of the knowledge of the LORD
as the waters cover the sea.
On that day the root of Jesse shall stand as a signal to the peoples; the nations shall inquire of him, and his dwelling shall be glorious.
Psalm 72:1-7, 18-19 Page 685, BCP
Give the King your justice, O God, *
and your righteousness to the King's Son;
That he may rule your people righteously *
and the poor with justice;
That the mountains may bring prosperity to the people, *
and the little hills bring righteousness.
He shall defend the needy among the people; *
he shall rescue the poor and crush the oppressor.
He shall live as long as the sun and moon endure, *
from one generation to another.
He shall come down like rain upon the mown field, *
like showers that water the earth.
In his time shall the righteous flourish; *
there shall be abundance of peace till the moon shall be no more.
Blessed be the Lord GOD, the God of Israel, *
who alone does wondrous deeds!
And blessed be his glorious Name for ever! *
and may all the earth be filled with his glory.
Whatever was written in former days was written for our instruction, so that by steadfastness and by the encouragement of the scriptures we might have hope. May the God of steadfastness and encouragement grant you to live in harmony with one another, in accordance with Christ Jesus, so that together you may with one voice glorify the God and Father of our Lord Jesus Christ.
Welcome one another, therefore, just as Christ has welcomed you, for the glory of God. For I tell you that Christ has become a servant of the circumcised on behalf of the truth of God in order that he might confirm the promises given to the patriarchs, and in order that the Gentiles might glorify God for his mercy. As it is written,
"Therefore I will confess you among the Gentiles,
and sing praises to your name";
and again he says,
"Rejoice, O Gentiles, with his people";
"Praise the Lord, all you Gentiles,
and let all the peoples praise him";
and again Isaiah says,
"The root of Jesse shall come,
the one who rises to rule the Gentiles;
in him the Gentiles shall hope."
May the God of hope fill you with all joy and peace in believing, so that you may abound in hope by the power of the Holy Spirit.
In those days John the Baptist appeared in the wilderness of Judea, proclaiming, "Repent, for the kingdom of heaven has come near." This is the one of whom the prophet Isaiah spoke when he said,
"The voice of one crying out in the wilderness:
`Prepare the way of the Lord,
make his paths straight.'"
Now John wore clothing of camel's hair with a leather belt around his waist, and his food was locusts and wild honey. Then the people of Jerusalem and all Judea were going out to him, and all the region along the Jordan, and they were baptized by him in the river Jordan, confessing their sins.
But when he saw many Pharisees and Sadducees coming for baptism, he said to them, "You brood of vipers! Who warned you to flee from the wrath to come? Bear fruit worthy of repentance. Do not presume to say to yourselves, `We have Abraham as our ancestor'; for I tell you, God is able from these stones to raise up children to Abraham. Even now the ax is lying at the root of the trees; every tree therefore that does not bear good fruit is cut down and thrown into the fire.
"I baptize you with water for repentance, but one who is more powerful than I is coming after me; I am not worthy to carry his sandals. He will baptize you with the Holy Spirit and fire. His winnowing fork is in his hand, and he will clear his threshing floor and will gather his wheat into the granary; but the chaff he will burn with unquenchable fire."
It is very interesting to note, in any case, that the Advent propers are identical in every respect in the ordinary and extraordinary forms; that is, these chant propers have been used continuously since at least the middle of the 16th Century - and I would suspect longer than that.
Other Advent 2 propers on Chantblog are discussed at these links:
Here's Michaelangleo's Isaiah, from the Sistene Chapel:
And this is a Russian icon of Isaiah, from the Iconostasis of Transfiguration church, Kizhi monastery, Karelia, Russia. It dates from the early 1700s: