The Breviary was not substantially changed, only the details were, so Pius X did not deviate from Pius V.  And Pius V did not deviate from his predecessors. 

It’s a false battle to pit Tradition vs Papal Authority because they are not enemies.  Quo Primum simply codified the mass as being part of Tradition, as St Pius V says that the essence of the rite goes all the way back to the early church and Pope St Gregory the Great. 

No Pope can substantially change the canon.  Does St Joseph’s addition substantially change the canon?  No.  But does it harm the idea of Tradition?  Yes.  Is such a harm allowable?  Probably, because it’s minor.  Is it a prudential act?  I’m sure, not.

Could a pope get rid of the entire Communicantes prayer?  I’m not sure. 

What I do know is that any revision to the liturgy would have to abrogate or revise Quo Primum, and that didn’t happen.  So the addition of St Joseph isn’t a fully legal change. 

I agree.

I already will admit that while I don't think so, the addition of St. Joseph, because of who he is, could be done legally. But to say Quo Primum does not mean what it says as regards the Roman Rite of the Mass, is to render Pope Paul VI, not blameless for it's replacement, but yes, completely blameless for doing away with it - there was nothing in place to stop him.

As Fr. Wathen says: "If we say that his successor is not bound by this legislation, we have to say that the Church has no way of protecting it’s own liturgy." Which is EXACTLY what Lad is saying - but apparently does not even realize it.
      
Quo Primum has the same meaning to Lad as it did to Pope Paul VI - no meaning whatsoever, not even worth mentioning.

If the law of Quo Primum does not mean what it says, then it's altogether meaningless and serves no purpose at all. It'd be as NOers attest to, "it was an old law that no longer applies." Or, "one pope cannot bind another pope." 

PPV made the law of Quo Primum the law forever for a reason, to say otherwise then you may as well embrace the NO and it's "mass."  

As Fr. Wathen says: "If we say that his successor is not bound by this legislation, we have to say that the Church has no way of protecting it’s own liturgy."

.

Protecting it from what? Of course Quo Primum binds anybody below the pope from tampering with the missal, but it doesn't bind a subsequent pope. But obviously the liturgy doesn't need to be protected from the pope, since the pope is the one doing the protecting, not the harming.

Protecting it from what? Of course Quo Primum binds anybody below the pope from tampering with the missal, but it doesn't bind a subsequent pope. But obviously the liturgy doesn't need to be protected from the pope, since the pope is the one doing the protecting, not the harming.

Protecting it from what happened when popes ignored the Law that protected it. 

No Pax, the point is that Lad says no pope can bind his successors,

The answer is, he can and he can't.  It depends.  You are arguing more for "can't" and Lad is arguing more for "can", but you're both wrong.  The answer remains - it depends.

The Breviary was not substantially changed, only the details were, so Pius X did not deviate from Pius V.  And Pius V did not deviate from his predecessors. 

It’s a false battle to pit Tradition vs Papal Authority because they are not enemies.  Quo Primum simply codified the mass as being part of Tradition, as St Pius V says that the essence of the rite goes all the way back to the early church and Pope St Gregory the Great. 

No Pope can substantially change the canon.  Does St Joseph’s addition substantially change the canon?  No.  But does it harm the idea of Tradition?  Yes.  Is such a harm allowable?  Probably, because it’s minor.  Is it a prudential act?  I’m sure, not.

Could a pope get rid of the entire Communicantes prayer?  I’m not sure. 

What I do know is that any revision to the liturgy would have to abrogate or revise Quo Primum, and that didn’t happen.  So the addition of St Joseph isn’t a fully legal change. 

Not true! The Breviary changes of St. Pius X were every bit as revolutionary as the Breviary changes made under Montini. A complete reording of the Psalter was introduced under Pius X ostensibly to reduced the burden on secular priests. This reform maintained a one-week cycle, whereas Montini's reform introduced a 4-week Psalter cycle. Nevertheless, as one who prays the Office is its pre-Pius X form, I can tell you that the Office of Pius X (and, later, the reformed Office of John XIII) is clearly the Roman liturgy in that the basic form is retained but the Office of Pius X has different content in those forms from what came before and dome content has been wholly excised.

There are no changes in the consecration prayers of the 1969 typical edition of the Roman Missal that cannot be found in the consecration prayers of other valid liturgical Rites.

The problem with the New Mass is its archaeologism and its novel, lab-created orations that are either substanial edits of older prayers or prayers of entirely new composition. Add to this a new calendar and a novel 3-year/2-year lectionary cycle and what one has is a Frankenstein liturgy.

The validity problem with the reforms of Montini really centre upon the form for the consecration of bishops. This is doubtfully valid, some may argue invalid, and has a down-stream effect on other sacraments.

I would also call out the removal of the Catholic Offertory and its replacement by a тαℓмυdic blessing / table prayer.

Wow! You are so wrong that my eyes weep for you!

The Roman Breviary is indeed the Roman liturgy, as too are the rites of the Roman Missal, the Roman Ritual, the Roman Pontifical. The contents of the Roman Gradual, the Roman Epistulary, the Roman Evangelary, and the Roman Martyrology also pertain to the Roman liturgy.

Where the Breviary is concerned, it constitutes the greater part of the daily liturgical action of the Church. In fact, the Mass id dependent upon the liturgical hours of the Breviary as to the time of morning that Mass is to be offered. In some seasons, Mass properly follows Terce, in Lent it follows Vespers transferred to morning, and at other time Mass is connected to Matins or Lauds.

Either post Pope St. Pius V's Papal Bull Quod a nobis or don't, but don't go on pretending that you know what it says until someone posts it here.

I would also call out the removal of the Catholic Offertory and its replacement by a тαℓмυdic blessing / table prayer.

Yes, indeed!!!