Council of Trent: Session 22
Chapter 6
On Mass wherein the priest alone communicates.
The sacred and holy Synod would fain indeed that, at each mass, the faithful who are present should communicate, not only in spiritual desire, but also by the sacramental participation of the Eucharist, that thereby a more abundant fruit might be derived to them from this most holy sacrifice: but not therefore, if this be not always done, does It condemn, as private and unlawful, but approves of and therefore commends, those masses in which the priest alone communicates sacramentally; since those masses also ought to be considered as truly common; partly because the people communicate spiritually thereat; partly also because they are celebrated by a public minister of the Church, not for himself only, but for all the faithful, who belong to the body of Christ.
Chapter 7
On the water that is to be mixed with the wine to be offered in the chalice.
The holy Synod notices, in the next place, that it has been enjoined by the Church on priests, to mix water with the wine that is to be offered in the chalice; as well because it is believed that Christ the Lord did this, as also because from His side there came out blood and water; the memory of which mystery is renewed by this commixture; and, whereas in the apocalypse of blessed John, the peoples are called waters, the union of that faithful people with Christ their head is hereby represented.
Chapter 8
On not celebrating the Mass every where in the vulgar tongue; the mysteries of the Mass to be explained to the people.
Although the mass contains great instruction for the faithful people, nevertheless, it has not seemed expedient to the Fathers, that it should be every where celebrated in the vulgar tongue. Wherefore, the ancient usage of each church, and the rite approved of by the holy Roman Church, the mother and mistress of all churches, being in each place retained; and, that the sheep of Christ may not suffer hunger, nor the little ones ask for bread, and there be none to break it unto them, the holy Synod charges pastors, and all who have the cure of souls, that they frequently, during the celebration of mass, expound either by themselves, or others, some portion of those things which are read at mass, and that, amongst the rest, they explain some mystery of this most holy sacrifice, especially on the Lord's days and festivals.
Chapter 9
Preliminary Remark on the following Canons.
And because that many errors are at this time disseminated and many things are taught and maintained by divers persons, in opposition to this ancient faith, which is based on the sacred Gospel, the traditions of the Apostles, and the doctrine of the holy Fathers; the sacred and holy Synod, after many and grave deliberations maturely had touching these matters, has resolved, with the unanimous consent of all the Fathers, to condemn, and to eliminate from holy Church, by means of the canons subjoined, whatsoever is opposed to this most pure faith and sacred doctrine.