Question Two: On the Requisites for Celebration

384. For licit celebration three things are required: 1. on the part of the body, immunity from a defect which impedes celebration and constitutes an irregularity from defect (can. 984, n. 2), - fasting (can. 808), - and cleanliness, as was explained above (n. 280-284); 2. on the part of the soul: the state of grace, after consciousness of mortal sin, proved by confession, as was said in n. 271-272 (can. 807), immunity from censure, irregularity, and other canonical penalties and impediments (can. 2261), and due preparation (can. 810); 3. on the part of external circumstances: observance of the ceremonies, rites, and other things prescribed by the Church.

385. The obligation of observing the ceremonies and rites and other precepts of the Church as to the celebration of the sacrifice is very grave. - For since nothing is holier than the sacrifice of the altar, the Church wills that it be offered with much apparatus and external worship, and therefore has prescribed many things concerning place or time, concerning the things to be used and the rites to be observed, so that the sacred action may be exercised with decorum, reverence, and piety, namely, as the Council of Trent says, sess. 22, c. 5: "both that the majesty of so great a sacrifice might be commended, and that the minds of the faithful, through these visible signs of religion and piety, might be stirred up to contemplation of the most lofty things which lie hidden in this sacrifice." Concerning this, see the Council of Trent, sess. 7, can. 13; sess. 22, c. 4 and 5, can. 7 and 9; and in the Code of Law, can. 733, 811, 818, 821 and 822.

The Church has ordained certain things which from received interpretation are held as merely directive, such as those which precede or follow Mass; but many are truly preceptive; among these, however, certain ones, by reason of the reverence due, are urged altogether strictly, so that never, or scarcely ever, would celebration without them be licit: thus the sacrifice could never be offered without a chalice, almost never without sacred vestments or outside an altar, rarely outside a sacred place.

386. It is a sin grave from its genus to change the prescribed rubrics of the sacrifice. - For it is the grave transgression of a precept of the Church; and indeed:

1. to add to the rubrics from an intention of changing or introducing a new rite is a grave sin, because it is to usurp the authority of the Church in a matter of great importance; but from indiscreet devotion, it is venial if the matter is slight, grave if notable;

2. to omit something from the rubrics notable of itself, containing a special signification, is grave by reason of quality; but to omit lighter ceremonies is venial, unless it is done in great part, in which case it is grave by reason of quantity.