In dulci iubilo

...let us our homage show;
our heart's joy reclineth
in praesepio,
and like a bright star shineth
matris in gremio,
Alpha es et O, Alpha es et O.

Yes, Aquinas, There is a Santa Claus (Touchstone)

O Jesu parvule,
I yearn for thee alway,
Hear me, I beseech thee,
O Puer optime!
My prayer let it reach thee,
O Princeps gloriae!
Trahe me post te, trahe me post te.

Hrodulf the Red-Nosed Reindeer (Old English Pages)

O Patris caritas,
O Nati lenitas!
Deeply were we stained
per nostra crimina,
But Thou hast for us gained
coelorum gaudia;
O that we were there, O that we were there.

The House of Christmas (G.K. Chesterton)

Ubi sunt gaudia,
In any place but there?
There are angels singing
nova cantica,
There the bells are ringing
in Regis curia;
O that we were there! O that we were there.

-14th century German