“Although the Mass contains much instruction for the faithful, it has nevertheless not seemed expedient to the fathers that it be celebrated everywhere in the vernacular. The holy synod commands pastors and everyone who has the care of souls to explain frequently during the celebration of the Masses, either themselves or through others, some of the things that are read in the Mass, and among other things to expound some mystery of this most Holy Sacrifice, especially on Sundays and feastdays.”
— Council of Trent, XII:8 (1562)