In answering the question, I rambled a bit [no surprise if you know me] and eventually read for them from Vatican II's Constitution on the Sacred Liturgy, paragraph 54:
"A suitable place may be allotted to the vernacular in Masses which are celebrated with the people ... Nevertheless care must be taken to ensure that the faithful may also be able to say or sing together in Latin those parts of the Ordinary of the Mass which pertain to them."
I think this surprised most of the people there. While most Catholics will tell you that "Vatican II called for the end of Latin", not many have heard that, when it comes to musical settings, through the years we were supposed to have been taught to be able to recite or sing the Gloria, Creed, Sanctus, Mortem Tuam (a.k.a. memorial acclamation), Our Father, and Lamb of God.
Hopefully by now the Catholic who attends Mass weekly knows that the English translation of Mass will be changing next Advent. Along with the prayers, we'll also be hearing new musical settings for the retranslated Mass propers. Along with the new settings in English, I think a golden opportunity exists to, about 50 years after the fact, implement what was called for by the Council.