Pope John XXII had some specific opinions on church music, which he expressed in his bull Docta sanctorum patrum.
But some disciples of a new school, occupying themselves with the measuring of time units, [now] signify with new notes, and prefer to make up their own rather than sing the old ones. The ecclesiastical [chants] are sung in semibreves and minims, and beaten with little notes. For they cut the melodies with hockets, make them slippery with discants, and sometimes add vernacular tripla and moteti, to such a degree that at times they spurn or disregard the very foundations of the Antiphonal and Gradual on which they build, [that they] are unaware of the church modes, which they do not distinguish but rather confuse, because the modest ascents and measured descents of the plainchant, by which those modes are distinguished from one another, are obscured by the multitude of those notes.
With all this, however, we do not intend to prohibit that once in a while, especially on feastdays and holidays, during Mass or in the aforesaid Holy Offices, some consonances that have the savor of melodious sound, such as octave, fifth, fourth, and others of this kind, be sung over the simple ecclesiastical chant—provided, however, that the integrity of the chant shall remain unimpaired, and that nothing of this well-ordered music be changed in any way. This above all because consonances of this kind soothe the hearing, stir devotion, and do not allow the minds of those who are singing to God to become torpid.Quoted in Rob Wegman, “What is counterpoint?” in Improvising Early Music (Leuven: Leuven Univeristy Press, 2014), 34-6.
There are many excellent commentaries on this text, such as the one cited just above, but one thing that flummoxes me, and continues to flummox me, about these sorts of texts is, why does John XXII care? He is no doubt a very busy pope, and quite apart from the various geo-political concerns of being a fourteenth-century pontiff, he is no doubt busy thinking about the teachings of the holy fathers and other important theological matters. Why does he choose to spend any time, let alone this much time, on details of “semibreves and minims,” “tripla and moteti,” and other such technical musical terms? This way of prioritizing the granular, structural details of music composition still shocks me to this day. This is a theme I will return to again, when it comes to Charlemagne.
If you are curious, here is some of the music John XXII might have been thinking of.