When I was in high school, way back in the dim distant past, I studied Latin. One year all of the language classes were asked to sing songs for a school occasion in the languages we were studying. The Latin class sang a couple of Christmas carols, the theme from Exodus (translated into Latin - mea terra, deus mihi dedit etc, or something like that), and Dona Nobis Pacem, which I loved immediately and have loved ever since. I think the melody is simple yet beautiful, sung as a melody and not as a canon, but I like the canon too.

Maybe someone later had the bright idea to sing it as a canon, rather than it being originally composed as a canon.

Helen