What this Motu Proprio is NOT

Before understanding what the content and implications of this decree, it is important to remember what it is not. Misunderstandings about the post-Vatican II liturgy abound, and it is vital to avoid these in reporting this:

1. The Motu Proprio does not "bring back the Latin Mass."

Why?

Because the "Latin Mass" never went away.

Many believe that the Second Vatican Council (1962-65) "abolished" the Latin Mass and required use of the vernacular in the Mass. This is just not true.

The root liturgical books of the Latin Rite of the Roman Catholic Church are still in Latin. It is called the Missale Romanum. When people pray the Mass in the vernacular they are praying a translation (approved by their national bishops' conference) of the Missale Romanum.

Any priest may celebrate Mass in Latin. In many parishes in the United States, you will find Masses in which parts are recited or chanted in Latin and even some in which the entire Mass is still celebrated in Latin, with Gregorian Chant.

In fact, the Bishops of the Second Vatican Council expected that Latin and Chant would still be used in the Mass, even if the rite ended up being revised (which it was.). The document related to the liturgy produced from the Second Vatican Council  - Sancrosanctum Concilium - expresses this expectation in several places:

36. 1. Particular law remaining in force, the use of the Latin language is to be preserved in the Latin rites.

2. But since the use of the mother tongue, whether in the Mass, the administration of the sacraments, or other parts of the liturgy, frequently may be of great advantage to the people, the limits of its employment may be extended. This will apply in the first place to the readings and directives, and to some of the prayers and chants, according to the regulations on this matter to be laid down separately in subsequent chapters.

and

54. In Masses which are celebrated with the people, a suitable place may be allotted to their mother tongue. This is to apply in the first place to the readings and "the common prayer," but also, as local conditions may warrant, to those parts which pertain to the people, according to tho norm laid down in Art. 36 of this Constitution.

Nevertheless steps should be taken so that the faithful may also be able to say or to sing together in Latin those parts of the Ordinary of the Mass which pertain to them.

and

116. The Church acknowledges Gregorian chant as specially suited to the Roman liturgy: therefore, other things being equal, it should be given pride of place in liturgical services.

But other kinds of sacred music, especially polyphony, are by no means excluded from liturgical celebrations, so long as they accord with the spirit of the liturgical action, as laid down in Art. 30.

Things changed very rapidly over the subsequent ten years as the new rite was formulated, but it is clear that the expectations of the Second Vatican Council were that any revisions would retain Latin, not only in the root books, but in common usage, even in Masses that included much of the "mother tongue" of the congregation, and that Gregorian Chant would be the first choice for music used during Masses.  They did not, on the whole, forsee a future in which both Latin and chant would disappear from ordinary parish Masses. To speak of the "liturgical spirit of Vatican II" as identified with unfettered creativity untethered from almost 2000-years of tradition is simply inaccurate.

2. This Motu Proprio does not impose the 1962 Missal on the present.

No priest will be required to celebrate the Mass from the 1962 Missal. The Mass of Paul VI, the fruit of the reforms called for by the Second Vatican Council, will still be the Mass most Catholics experience.