From the Catholic Encyclopedia
“…The third Sunday of Advent, so called from the first word of the Introit at Mass (Gaudete, i.e. Rejoice). The season of Advent originated as a fast of forty days in preparation for Christmas, commencing on the day after the feast of St. Martin (12 November), whence it was often called “St. Martin’s Lent”– a name by which it was known as early as the fifth century. The introduction of the Advent fast cannot be placed much earlier, because there is no evidence of Christmas being kept on 25 December before the end of the fourth century (Duchesne, “Origines du culte chrétien”, Paris, 1889), and the preparation for the feast could not have been of earlier date than the feast itself. In the ninth century, the duration of Advent was reduced to four weeks, the first allusion to the shortened season being in a letter of St. Nicholas I (858-867) to the Bulgarians, and by the twelfth century the fast had been replaced by simple abstinence. St. Gregory the Great was the first to draw up an Office for the Advent season, and the Gregorian Sacramentary is the earliest to provide Masses for the Sundays of Advent. In both Office and Mass provision is made for five Sundays, but by the tenth century four was the usual number, though some churches of France observed five as late as the thirteenth century. Notwithstanding all these modifications, however, Advent still preserved most of the characteristics of a penitential seasons which made it a kind of counterpart to Lent, the middle (or third) Sunday corresponding with Laetare or Mid-Lent Sunday. On it, as on Laetare Sunday, the organ and flowers, forbidden during the rest of the season, were, permitted to be used; rose-coloured vestments were allowed instead of purple (or black, as formerly); the deacon and subdeacon reassumed the dalmatic and tunicle at the chief Mass, and cardinals wore rose-colour instead of purple. All these distinguishing marks have continued in use, and are the present discipline of the Latin Church. Gaudete Sunday, therefore, makes a breaker like Laetare Sunday, about midway through a season which is otherwise of a penitential character, and signifies the nearness of the Lord’s coming. Of the “stations” kept in Rome the four Sundays of Advent, that at the Vatican basilica is assigned to Gaudete, as being the most important and imposing of the four. In both Office and Mass throughout Advent continual reference is made to our Lord’s second coming, and this is emphasized on the third Sunday by the additional signs of gladness permitted on that day. Gaudete Sunday is further marked by a new Invitatory, the Church no longer inviting the faithful to adore merely “The Lord who is to come”, but calling upon them to worship and hail with joy “The Lord who is now nigh and close at hand”. The Nocturn lessons from the Prophecy of Isaias describe the Lord’s coming and the blessings that will result from it, and the antiphons at Vespers re-echo the prophetic promises. The joy of expectation is emphasized by the constant Alleluias, which occur in both Office and Mass throughout the entire season. In the Mass, the Introit “Gaudete in Domino semper” strikes the same note, and gives its name to the day. The Epistle again incites us to rejoicing, and bids us prepare to meet the coming Saviour with prayers and supplication and thanksgiving, whilst the Gospel, the words of St. John Baptist, warns us that the Lamb of God is even now in our midst, though we appear to know Him not. The spirit of the Office and Liturgy all through Advent is one of expectation and preparation for the Christmas feast as well as for the second coming of Christ, and the penitential exercises suitable to that spirit are thus on Gaudete Sunday suspended, as were, for a while in order to symbolize that joy and gladness in the Promised Redemption which should never be absent from the heart of the faithful….”
The wilderness and the dry land shall be glad,
the desert shall rejoice and blossom;
like the crocus it shall blossom abundantly,
and rejoice with joy and singing.
The glory of Lebanon shall be given to it,
the majesty of Carmel and Sharon.
They shall see the glory of the LORD,
the majesty of our God.
Strengthen the weak hands,
and make firm the feeble knees.
Say to those who are of a fearful heart,
“Be strong, do not fear!
Here is your God.
He will come with vengeance,
with terrible recompense.
He will come and save you.”
Then the eyes of the blind shall be opened,
and the ears of the deaf unstopped;
then the lame shall leap like a deer,
and the tongue of the speechless sing for joy.
For waters shall break forth in the wilderness,
and streams in the desert;
the burning sand shall become a pool,
and the thirsty ground springs of water;
the haunt of jackals shall become a swamp,
the grass shall become reeds and rushes.
A highway shall be there,
and it shall be called the Holy Way;
the unclean shall not travel on it,
but it shall be for God’s people;
no traveler, not even fools, shall go astray.
No lion shall be there,
nor shall any ravenous beast come up on it;
they shall not be found there,
but the redeemed shall walk there.
And the ransomed of the LORD shall return,
and come to Zion with singing;
everlasting joy shall be upon their heads;
they shall obtain joy and gladness,
and sorrow and sighing shall flee away.
Psalm 146:4-9 Page 803, BCP
Lauda, anima mea
Happy are they who have the God of Jacob for their help!*
whose hope is in the LORD their God;
Who made heaven and earth, the seas, and all that is in them; *
who keeps his promise for ever;
Who gives justice to those who are oppressed, *
and food to those who hunger.
The LORD sets the prisoners free;
the LORD opens the eyes of the blind; *
the LORD lifts up those who are bowed down;
The LORD loves the righteous;
the LORD cares for the stranger; *
he sustains the orphan and widow,
but frustrates the way of the wicked.
The LORD shall reign for ever, *
your God, O Zion, throughout all generations.
The Song of Mary Magnificat
My soul proclaims the greatness of the Lord,
my spirit rejoices in God my Savior; *
for he has looked with favor on his lowly servant.
From this day all generations will call me blessed: *
the Almighty has done great things for me, and holy is his Name.
He has mercy on those who fear him *
in every generation.
He has shown the strength of his arm, *
he has scattered the proud in their conceit.
He has cast down the mighty from their thrones, *
and has lifted up the lowly.
He has filled the hungry with good things, *
and the rich he has sent away empty.
He has come to the help of his servant Israel, *
for he has remembered his promise of mercy,
The promise he made to our fathers, *
to Abraham and his children for ever.
Glory to the Father, and to the Son, and to the Holy Spirit: *
as it was in the beginning, is now, and will be for ever. Amen.
Be patient, therefore, beloved, until the coming of the Lord. The farmer waits for the precious crop from the earth, being patient with it until it receives the early and the late rains. You also must be patient. Strengthen your hearts, for the coming of the Lord is near. Beloved, do not grumble against one another, so that you may not be judged. See, the Judge is standing at the doors! As an example of suffering and patience, beloved, take the prophets who spoke in the name of the Lord.
When John heard in prison what the Messiah was doing, he sent word by his disciples and said to him, “Are you the one who is to come, or are we to wait for another?” Jesus answered them, “Go and tell John what you hear and see: the blind receive their sight, the lame walk, the lepers are cleansed, the deaf hear, the dead are raised, and the poor have good news brought to them. And blessed is anyone who takes no offense at me.”
As they went away, Jesus began to speak to the crowds about John: “What did you go out into the wilderness to look at? A reed shaken by the wind? What then did you go out to see? Someone dressed in soft robes? Look, those who wear soft robes are in royal palaces. What then did you go out to see? A prophet? Yes, I tell you, and more than a prophet. This is the one about whom it is written,
`See, I am sending my messenger ahead of you,
who will prepare your way before you.’
Truly I tell you, among those born of women no one has arisen greater than John the Baptist; yet the least in the kingdom of heaven is greater than he.”