Liturgy the "supreme expression of priestly life"

"Liturgical worship is the supreme expression of priestly and episcopal life, and also of catechetical teaching. Your mission of sanctification of the faithful people, dear Brothers, is indispensable for the growth of the Church. I was prompted to detail, in the Motu proprio Summorum Pontificum, the conditions for the accomplishment of this mission, in that which relates to the possibility of using both the missal of Blessed John XXIII (1962) and that of Pope Paul VI (1970). The fruits of these new dispositions have already seen [the light of] day, and I hope that the indispensable pacification of the spirits is being accomplished, thank God."

Pope Benedict to the Bishops of France, 14 September 2008