Vatican website translation:
50. The rite of the Mass is to be revised in such a way that the intrinsic nature and purpose of its several parts, as also the connection between them, may be more clearly manifested, and that devout and active participation by the faithful may be more easily achieved.
For this purpose the rites are to be simplified, due care being taken to preserve their substance; elements which, with the passage of time, came to be duplicated, or were added with but little advantage, are now to be discarded; other elements which have suffered injury through accidents of history are now to be restored to the vigor which they had in the days of the holy Fathers, as may seem useful or necessary.
50. Ordo Missae ita recognoscatur, ut singularum partium propria ratio necnon mutua connexio clarius pateant, atque pia et actuosa fidelium participatio facilior reddatur.
Quamobrem ritus, probe servata eorum substantia, simpliciores fiant; ea omittantur quae temporum decursu duplicata fuerunt vel minus utiliter addita; restituantur vero ad pristinam sanctorum Patrum normam nonnulla quae temporum iniuria deciderunt, prout opportuna vel necessaria videantur.
Slavishly literal translation [kindness of Jonathan Day]
50. The Order of Mass is to be reviewed and revised in such a way that the particular plan of each of its parts, as well as the connection between them, may become more clearly accessible, and that the devout and active participation of the faithful may be more easily restored.
To this end the rites, with due care to preserve their substance, are to be made more simple; those things are to be set aside that, with the passage of time, came to be duplicated or were added with little advantage; the many things that suffered the injuries of time are truly to be restored to the original [old-time] standard of the holy Fathers, as may seem useful or necessary.
Having articulated the rationale for reforming the celebrational structure of [Roman Rite] Eucharist in arts. 47-49, art. 50 begins a set of reform decrees dedicated to that end. This article is the most far-reaching, with subsequent articles concentrating on particular aspects of reform of the Order of Mass.
Notice that Jonathan Day’s translation of “recognoscatur” as “reviewed and revised” helpfully encompasses the directives entrusted to the reform bodies: the history of the Order of Mass is to be explored for its fundamental structure and its celebrational structure is to be changed on the basis of some overarching principles. First, the “singularum partium propria ratio” [rendered by Mr. Day as “particular plan of each of its parts”] and their “mutual connexio” [“the connection between them”] are to be made “clarius pateant” [“more clearly accessible”]. Second, this review and revision is directed so that the “pia et actuosa fidelium participatio” [“devout and active participation of the faithful” might be “facilior reddatur” [“more easily restored/given back/returned/achieved”].
At the risk of underlining the obvious (and possibly causing a firestorm among Pray Tell readers), this initial decree suggests that the Council Fathers had judged that the Order of Mass as celebrated according to the Missale Romanum 1962 did not clearly manifest the structure of its component elements nor the connections between those elements. They further held that making that structure and connections more evident to worshipers could or would enhance their participation. I see nothing in the article that suggests that the Council Fathers believed two celebrational forms of Roman Rite Mass should co-exist: one reformed to make its structure and the interrelation of its components more clear for the sake of the faithful’s participation and one judged defective in its structure and the interrelation of its components.
To guide this general review and revision of the Order of Mass, the Council Fathers then propose the following:
1) Without losing the substance of the rites, a simplified form of the Order of Mass should be produced. Perhaps the easiest way to illustrate this change is to compare the rites prior to the Epistle in the Missale Romanum 1962 with the Introductory Rites in the Missale Romanum 1970ff or the rites following communion in the former with the Concluding Rites in the latter. I suspect there are great differences of opinion among Pray Tell readers about what constitutes “preserving the substance of the rites” and to what extent simplicity in the execution of the rites corresponds the human exigencies of ritual behavior.
2) Duplications and questionable additions were to be removed from the Order of Mass. An example of removal of duplications added over the course of time would be the reduction of multiple signs of the Cross made during the recitation of the Canon of the Mass according to the Missale Romanum 1570-1962 to a single sign of the Cross over the elements made during the recitation of a Eucharistic Prayer according to the Missale Romanum 1970ff. An example of removal of a questionable addition would be the elimination of the Last Gospel in the Missale Romanum 1970ff. I suspect that there may be great differences of opinion among Pray Tell readers about what constitute “duplications and questionable additions” in the Order of Mass. It would be interesting to try to discover what principles guided the coetus a studiis who proposed the reformed Order of Mass and how those principles play out in practice in the light of a half century of experience with the reformed Order of Mass.
3) Finally, as may seem useful or necessary, elements in the Order of Mass that have fallen into desuetude are to be restored. Examples might be the use of vernacular languages or the re-introduction of the Universal Prayer/Prayer of the Faithful or an increase in the number of Eucharistic Prefaces. I suspect that there might be differences of opinion among Pray Tell readers about what elements of past Eucharistic celebrations (e.g., lavish use of sequences) might be appropriate for restoration.