Ah, that leads to a nice rabbit hole. Would this have been sung (inappropriately) during the Mass? If so, do you know where or when (ie after Communion, during the Offertory, etc.)?

Palestrina obviously knew they should stay out of the liturgy.

Nonetheless, it's an ideal example in my mind because it's not obviously worldly (like a madrigal), it takes words from the Bible in Latin, and it's in a Renaissance style--qualities that any layperson would assume makes it suitable for the liturgy--yet it isn't.

I can't think of any Masses that have stuck around in popular use which are a parody or paraphrase of inappropriately secular material (unless you count the billion "Misse L'Homme Arme")

I'd be afraid they'd just draw the conclusion that the church can't make up its mind. Eslava's 1854 organ method gives some pretty hilarious examples of cadences to avoid, on page 25.

@oldhymns, yes those I am aware of. The older repertory I'm less familiar with. Funny: I grew up playing classical music, but always in a secular context (recitals, concerts, etc.). One day many decades later (after converting) I went to a Mass in which the music was Mozart's famous Requiem. I think my mouth hung open the entire time. It had never dawned on me that all those "Masses" I'd heard or we played in orchestra were anything to do with MASS. It literally had never clicked. I loved it. But I do think it is not prayerful - too stimulating to the senses, too overwhelming of the subtlety of the ceremony, distracting.

I find some Renaissance polyphony too noisy, too complex and hard to listen to, too, actually. Like everyone talking at once over the dinner table? Shhhhhhhhh.

@RichardMix (and igneus), I think we (people in the group I'll be giving the talk to) all are well aware of that - most of us assist in home parishes during the week where the musical choices are very poor; and on weekends most assist at EF Masses or reverently celebrated OF Masses and are learning the basics Gregorian chant. The idea is to give an overview of why we want to throw our hearts into learning chant, despite what our friends and neighbors back in our parishes might say; and why we musn't despair, because the Church has always struggled with these problems. Ongoing messiness seems to be part of the human condition. God's mercy is all the more evident given how shabbily we treat Him.

In 1922, the Society of St. Gregory, a precursor of CMAA, published a list of music considered not in keeping with the liturgical ideals expressed in papal teaching: that is, in Pope Pius X's document "Tra le sollecitudini", which encouraged chant and discouraged music that imitated theatrical styles.

Here's the list: https://media.musicasacra.com/pdf/blacklist.pdf

Some great composers' works were respected, but still deemed unsuitable for use in the liturgy, although they would still be suitable for concert performance: Verdi, Mozart, Rossini.

Some popular devotional hymns appear on the list: "Mother dearest, mother fairest", "Good night, sweet Jesus", "Mother dear, O pray for me". They might be acceptable for use in novena services or other non-liturgical occasions, but not in the Mass. The critique of such songs would probably be based on their musical style, which was considered to resemble sentimental popular songs of the time. If the tune sounds like it could segue right into "I'll take you home again, Kathleen", the style is too theatrical, hence worldly.

A present-day analogy would involve songs that sound as though they could be theme songs for TV shows, commercial jingles, or songs from musical theater.

@Richard Mix

Which canon of the Council of Trent abolished Sequences?

I'm playing advocatus diaboli but you might look at Coppini's contrafacta, surely thought appropriate by enough customers to guarantee a print run. One can't really say its sole purpose is pleasure, nor fault the text declamation even if the believer's gratitude for Christ's wounds was originally Dorinda's relief at finally having her love requited.

In 2009 we performed that Haydn Mass at the Colloquium in Chicago, with an extended version of the Gloria, modified to use the full text.
http://music.dierschow.com/2009Colloquium/26Mass/Gloria.mp3

The polytextual motets (above) are just bizarre. Were they trying to save time in Mass by singing everything at once, or was it an exercise in musical cleverness?

If the priest is responsible for the Gloria text
then whatever the choir does at the moment is soundtrack
therefore it might be nice to end the music when the scene changes.

...(like Shakespeare)...

Is it now a certainty, rather than speculation, that the Bard was Catholic?
Too, while admiring your zeal, I question your veracity: can one really maintain that being Catholic endowed writers, sui generis, with the capacity to compose multi-layered thought and that being Protestant meant that such endowments were ipso facto absent? This assertion is, I think, highly debatable - to say the least. Edmund Spencer, for one, comes to mind. Then, there is the layered mystical imagery in much hymnody of the late Renaissance and Baroque eras, both Catholic and Lutheran. The hymns of Paul Gerhardt and Johann Franck come to mind.

My website Catholic Romantic Music has a multitude of examples in score form, though I have very few media links. (One occasionally finds YouTubes from choirs in Asia, which seems to be where old Masses go to die.) Most of the performed examples are not egregious (Nobody has taken on Gilsinn's Grand Italian Mass, in which various bits of the bel canto opera repertoire get contrafacted.) There are a fair number of youtubes of La Hache whom Montani blacklisted. A good way to approach this would be to look at the Society of St. Gregory's Black List and chase down recordings. Even then, there are issues: Kalliwoda's music got blacklisted, but there are some a capella Masses discovered after Montani's time which are quite appropriate.

You can't legislate taste, and Mother Church is loath to legislate anything that doesn't have to be legislated.

What about the hocket? a kind of hiccup effect used by medieval church musicians. Try googling:
PDF Pope John XXII, Docta sanctorum patrum - Cengage
to find out what Pope John XXII (in office1316-1334) had to say about it. Here are a couple of examples (hope this works)