This is, for me, one of the most beautiful Advents songs ever. It dates from the 16th century in Geneva.
Music: Louis Bourgeois. Text: Johannes G Olearius. Translation: Catherine Winkworth
Here are the words of the hymn:
Comfort, comfort now my people;
speak of peace: so says our God.
Comfort those who sit in darkness,
mourning under sorrow’s load.
Cry out to Jerusalem
of the peace that waits for them;
tell her that her sins I cover
and her warfare now is over.
For the herald’s voice is crying
in the desert far and near,
calling all to true repentance,
since the kingdom now is here.
Oh, that warning cry obey!
Now prepare for God a way!
Let the valleys rise to meet him
and the hills bow down to greet him.
Then make straight what long was crooked;
make the rougher places plain.
Let your hearts be true and humble,
as befits his holy reign.
For the glory of the Lord
now on earth is shed abroad,
and all flesh shall see the token
that God’s word is never broken.