From the recording Winter and the Sacred Tree - A Live Concert Recording
This beautiful hymn is from the LIBER USUALIS.
It is sung at Vespers on Christmas Day.
Lyrics
Hodie Christus nátus est:
hodie Salvátor appáruit
Hodie in térra canunt Angeli,
laetántur Archángeli:
Hodie exsúltant jústi, dicéntes:
Glória in excélsis Déo, allelúia.
This day Christ is born,
this day the Saviour has appeared;
this day Angels sing praise on Earth,
the Archangels are rejoicing;
this day the righteous are glad and say,
Glory to God in the highest, alleluia.