Giovanni Pascoli (1855-1912) was a teacher of Classics (Greek and Latin) and later the chair of literature at the University of Bologna, following his mentor Carducci. A poet and a Dante scholar, he also wrote poetry in Latin, knowing very well that this was a DEAD language.
I was interested in this, as a nineteenth-century Italian poet writing in Latin seemed somewhat like somebody like Natsume Soseki (1817-1916), the greatest Japanese modern novelist, writing "kanshi," poetry composed in Classical Chinese. This is the kind of culture that was lost forever after Soseki's generation. (I can only think of Ishikawa Jun [1899-1987] as a younger-generation homme de lettre who could actually compose kanshi.)
Here is what I encountered in Giorgio Agamben's essay on Pascoli:
[...] polemicizing against the proposal to abolish the instruction of Greek in schools, Pascoli writes, "the language of poets is always a dead language," and immediately adds, "a curious thing---a dead language used to give greater life to thought" (The End of the Poem, tr. Daniel Heller-Roazen, p.62.)
A dead language's power to empower comes from its distance from the currently circulating language. In this sense, we may say that the "past is a foreign country," and project this chronological distance onto the synchronic plane to tentatively conclude: a foreign language can give greater life to thought.
Of course, if a foreign word was completely meaningless to the reader, it wouldn't have such a poetic power. The kind of foreign words to be dynamically meaningful within a new context are already translated---to the degree of being half-comprehensible, half-unpenetrable.
This may turn out to be the general logic of "xenoglossia." In translational poetics, under the influence of the original, foreign text, the translated text is charged with this half-meaning, that offers itself to a variety of acceptations. Like a stranger's glossolalia, half-translated foreign words can become seeds for a heightened verbal sensitivity.