Jon, thanks for these.

It’s also worth noting that many of the other major Christian Churches also maintain hieratic languages for worship: Old Church Slavonic, Coptic, etc. No one freaks out in Egyptian Churches when a hymn is sung in Coptic, regardless of whether the congregation understands it.

I think this is a point we often overlook because most Westerners (understandably) think “other Christian churches” refers to Protestants, but as Catholics it makes much more sense, theologically and historically, to think of other “Churches” as the Orthodox Churches.

Many otherwise vernacular mediaeval books (e.g., Langland's Piers Plouwman, et al.) are chock full of Latin and references to holy writ, as were mediaeval sermons, which were at least nominally in the 'vernacular'. This leads one to conclude that (contrary to the Protestant trope and common mis- perceptions) mediaeval people, even average people, had at least a moderate understanding of Latin. They could hardly have attended mass all their lives, participated in countless mystery plays and processions, sang macaronic carols, and been around literati who spoke Latin every day, without acquiring some ability to understand, quote, and even speak at least some form of Latin. Even every-day speech was peppered with Latin. Latin, after all, was not nearly as 'dead' then as it is now. It was, as yet, a fact of every day existence.

In fact, I am on the verge of ordering a new book which treats of this very subject. It is Preaching and Teaching in the Mediaeval Church, by Christopher Cannon, Oxford UP. Some others here may want to acquire this book, which, judging from the review, promises to be quite a significant contribution to the subject.