T IS A QUESTION of two conflicting values. Undoubtedly, Latin has been the language of the Latin liturgy for 1,600 years. It is a sign and source of unity as well as a defense of doctrine, not because of the language so much, but because it is a language no longer subject to changes. There are so many beautiful texts which can never have the same effectiveness in translation. Lastly, Latin is bound to an extremely precious heritage of melody: Gregorian chant and polyphony. On the other hand, it is beyond doubt that if we wish to bring the faithful, all the faithful, to a direct conscious and active participation in the liturgy, then we must speak to them in the language which they speak.
The Constitution [Second Vatican Council, Sacrosanctum Concilium: 1963] chose the only solution possible in this case: that of a compromise. Certain parts of the Mass, such as the Canon, remain in Latin, while others, especially those directed to the people, such as the readings and the restored Oratio fidelium, can take place in the vernacular.
SOURCE: The Development of the Liturgical Reform: As Seen by Cardinal Ferdinando Antonelli from 1948 to 1970