Gaudete! Christus est natus ex Maria Virginae!

Gaudete,
  gaudete!
Christus
  est natus
  Rejoice,
    rejoice!
  Christ
    is born
Ex Maria
  virgine,
  gaudete!
  Of Mary
    the Virgin — rejoice!

Tempus adest gratiæ
  The time of grace has come
Hoc quod optabamus,
  This that we have desired,
Carmina lætitiæ
  Verses of joy
Devote reddamus.
  Let us devoutly return.

Deus homo factus est
  God has become man,
Natura mirante,
  Nature marveling,
Mundus renovatus est
  The world has been renewed
A Christo regnante.
  By the reigning Christ.

Ezechielis porta
  The closed gate of Ezechiel
Clausa pertransitur,
  Is passed through,
Unde lux est orta
  Whence the light is born,
Salus invenitur.
  Salvation is found.

Ergo nostra contio
  Therefore let our gathering
Psallat iam in lustro;
  Now sing in brightness
Benedicat Domino:
  Let it give praise to the Lord:
Salus Regi nostro.
  Greeting to our King.

“Gaudete” (pronounced gow-DAE-tae, "rejoice" in Latin) is a sacred Christmas carol, composed sometime in the 16th century. The song was published in the Piae Cantiones, a collection of Finnish/Swedish sacred songs published in 1582. No music is given for the verses, but the standard tune comes from older liturgical books.

The text, in Latin, is a typical song of praise, probably stemming from the Middle Ages. It follows the standard pattern for the time - a uniform series of four-line stanzas, each preceded by a two-line refrain (in the early English carol this was known as the "burden"). Carols could be on any subject, but typically they were about the Virgin Mary or the Saints of Christmas.

And tonight, we rejoice, for God is with us.