Do Riu Riu Chiu! It's either 16th or 17th century, so it is early enough, and it's wonderful. It's in the new Oxford Book of Carols. It talks about God protecting the Virgin Mary from the devil so she can conceive and deliver Jesus, using the imagery of a shepherd and a wolf. The music is very haunting.

It's on Bruce Cockburn's "Christmas" CD also.

Riu riu chiu, la guarda ribera,
Dios guardo el lobo de nuestra cordera...

Alex
O..O
=o=