An old post which I am reprinting not least because of a highly interesting Comment
Low Sunday has passed; we are now again using hymns in our Office. If you are accustomed to the Liturgia Horarum, and if you look in a 1961 Breviary, you will get a shock when you got to the Office Hymn for Vespers during Eastertide. Instead of Ad cenam agni providi you will find Ad regias agni dapes. This text is the piece of elegant Renaissance Latinity which Urban VIII substituted for the the fifth century text previously in use. The problem Pope Urban had with the original is that it was written when Latin was still a spoken language, a living and vivid vernacular, and its text is therefore, from the point of view of classical purists, full of irregularities. For example, it treats stolis albis candidi [bright with white garments] as if it were istolis albis candidi (eight syllables): ist- is how they pronounced st- in the 'Vulgar Latin' period*. Like many popular and subclassical texts, strongly influenced by a basically 'oral' culture, the original form of this hymn has anacoloutha, diminutives, and 'intolerably' erratic systems of accented syllables. All this is why I like it. I even have a personal theory that the author was a considerable poet who actually used 'irregular' accentual patterns to emphasise words.
Urban's gang of resurrected Horaces so rewrote the second stanza that not a word of the original remained ... but perhaps by this point I have lost non-latinists. Never mind. If you have your English Hymnal [the finest English Language hymnal there is; one of the Patrimony's principal gifts] to hand, you can find the original, translated by the incomparable John Mason 'Patrimony' Neale, at 125. You will find the Urbanist replacement at 128. You may feel that both, in their different ways, are good hymns. In my opinion, you are right, at least as far as the Latin original of 128 is concerned (the great Adrian Fortescue disagreed: for him, there was not one single good word to be said for Pope Urban's hymns, and their elimination, he felt, should be the first element in a reform of the Breviary). I just happen to feel that Sacrosanctum Concilium of Vatican II was indeed wise to mandate the restoration of the original texts of the hymns (although the Dom Anselmo Lentini's 1968 revisers, foolishly, did straighten out the rhythms a bit). The Benedictines, incidentally, never did adopt the Urbanist texts.
Moreover, the Renaissance version can miss things. Neale was convinced that the old text's description of Christ's blood as 'rosy' (roseo: 'light pink', because Roman roses were not modern cultivars) is explained by that fact that if a body is totally drained of blood, the last few drops are ... pink (how did he know? Was he right?).
*Grandgent writes thus about this prosthetic vowel: "The earliest Latin example is probably iscolasticus, written in Barcelona in the second century; it is found repeatedly, though not frequently, in the third century; in the fourth and fifth it is very common: espiritum, ischola, iscripta, isperabi ..." Isidore of Seville in the seventh century was the first to comment on it. It has, of course, left innumerable marks upon the lexicography of the Romance languages (e.g. stella became istella which became estaile which became etoile).