AlexV:
But, then again, you betray your prejudice when you refer to the Novus Ordo Missal as “the current” Missal. That needs qualification. There are people for whom the 1962 is the “current” Missal.

The prejudices you speak of are apparently so deeply engrained in my subconscious that I didn’t know they existed.
To the best of my knowledge I don’t have any problem with people attending Indult, Ambrosian, Carthusian, Mozarabic Masses. None whatsoever. By way of justification I spent my two month summer holiday typing out the common and proper Masses of saints from my 1954 missal for subsequent editing and posting by a former FSSP seminarian. If you PM me with your email address I’ll be happy to send you the documents since he has apparently not yet got to editing the complete thing.
Kindly accept my apologies and replace “current missal” with “latest edito typica of the Roman Missal a.k.a. the Novus Ordo”
No, it is not correct to say the pope can simply “erase” whatever he pleases in 1500+ years of tradition and “you must obey”.
Oh, yes, I definitely don’t believe that a Pope should do it.
The pope could not announce tomorrow that we will gather on Sunday and say the words of institution, and nothing else, and that’s the new order of Mass.
As for the breviary of Pius V, the changes in the Psalter were purely done to allow for the full celebration of both the sanctoral (which is always increasing in size) and the temporal (which remains fixed).
OK fine, so why didn’t he just change the rubrics to allow the psalms of ferial days, etc. to be said on Double feasts and below (which he did anyway with his new psalter)? Why re-write the psalter? Why suppress institutions like the Laudate psalms that according to Baumstark went back to the early Apostolic age and maybe even back to Christ? Why suppress an ancient schema well over 1500 years old even at his day, in favour of a schema drafted by experts which had more in common with the neo-Gallcian breviaries of 18th century France? Why destroy the links that existed between the Roman and Eastern Offices in the matter of psalm 118 and the distribution of psalms at Lauds and Vespers?
The Psalter’s basic principle, as noted in the general rubrics of the 1568 Breviary, was all the psalms in one week. That goes back to Benedict’s Rule. That rule was not changed in the Roman Breviary ever until…oh, guess what, 1971.
What about the rules for ending Lauds with 148, 149, 150, the complete revolution in assignment of psalms, assigning those traditionally said for Matins to Compline and destroying the ratio in which psalms were arranged? What about the elimination of the distinctions between festal, ferial and Sunday offices?
As for the Offertory…I have a facsimile of the Offertory prayer for the water mingled with wine, which, as you note, does indeed come from the Christmas Mass (or vice versa…Christmas took it from the Offertory…probably the latter, though scholars disagree on that). The Gelasian Sacramentary also contains…amazingly…fragments of the offering prayer over the wine AND the invocation of the Spirit which appear fully at the earliest surviving date in manuscripts from the Strasbourg Cathedral library (= Gallican or Gallo-Romano). What 1970 did to the Offertory was not “business as usual”. The problem is the Gelasian Sacramentary is FRAGMENTARY. But that doesn’t mean what isn’t there wasn’t in existence. It means we have a more complicated, less sure footing.
I thoroughly affirm to almost 99% certainty that there was no such prayer at the Offertory. Give me the quote and I’ll eat my hat (which I do anyway nowadays what with all my mistakes

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Alex, I’ve NEVER read about the Collect being borrowed from the Offertory, and pardon mean as if I regard it as highly improbable. Would you mind telling me which scholars support that view and regard it as more “probable”? I would be very interested in knowing. Bishop, Cabrol, Fortescue and Jungmann all say the latter i.e. the offertory is an adaptation of the Collect. This seems highly probable to me, despite my rudimentary liturgical knowledge because:
In the earliest books (Leonine) a similar thing appears in the following form:
Deus, qui in humanae substantiae dignitate et mirabiliter condedisti et mirabilius reformasti: da, quaesumus, nobis Iesu Christi filii tui eius diuinitatis esse consortes, qui humanitatis nostrae fieri dignatus est particeps
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