The 'O Antiphons' (an antiphon is a spoken response in a church service) have been used in liturgical Christian traditions since as far back as the sixth century. They are spoken before reading the Magnificat at Evening Prayer during the last seven days of Advent.
My thanks to Malcolm Guite for these poetic reflections. Here is the one for 22nd December: O Rex Gentium – O Sovereign of the nations
O Rex Gentium
O Rex Gentium, et desideratus earum,
lapisque angularis, qui facis utraque unum:
veni, et salva hominem,
quem de limo formasti.
O King of the nations, and their desire,
the cornerstone making both one:
Christ in majesty, 13-14th-century mosaic, baptistery, Florence Come and save the human race,
which you fashioned from clay
O King of our desire whom we despise,
King of the nations never on the throne,
Unfound foundation, cast-off cornerstone,
Rejected joiner, making many one,
You have no form or beauty for our eyes,
A King who comes to give away his crown,
A King within our rags of flesh and bone.
We pierce the flesh that pierces our disguise,
For we ourselves are found in you alone.
Come to us now and find in us your throne,
O King within the child within the clay,
O hidden King who shapes us in the play
Of all creation. Shape us for the day
Your coming Kingdom comes into its own.