OR SEVERAL YEARS, Christoph Tietze along with many others have been trying to explain why the antiphons in the Graduale Romanum do not always match the antiphons in the Roman Missal. I, myself, have attempted to explain this in a series of articles [url] posted on the CCW website. However, it would seem that a whole lot of confusion still exists. For instance, today on the Musica Sacra Forum (which I visit quite frequently) some correspondence with the USCCB Committee on Divine Worship was posted here [jpeg] and here [jpeg]. To make a long story short, the Committee itself does not seem to be cognizant of the reason for discrepancies between some antiphons in the Graduale Romanum and the Roman Missal. I have to admit I am surprised to hear this, because several organizations have written to the Committee about this over the years, including the Roman Catholic Cathedral Musicians [homepage], and the relevant quote from Pope Paul VI is even printed in the front of the Roman Missal, 3rd Edition.
They are certainly not alone. One of the great liturgical scholars of all time, Professor László Dobszay, did not understand why the differences exist. I say this based on my understanding of part of his 2003 article [pdf] in the Sacred Music Journal, an excerpt of which I reproduce here:
As a matter of fact, there is a very good reason why these discrepancies exist. SHORT ANSWER: the antiphons in the Roman Missal were only to be used for “Masses without music” according to Pope Paul VI.
* For those who desire to learn more, please consider reading a series of articles [url] I have posted online.