Multilingualism played an important role in the establishment, during the fourth century A.D., of Christianity as the dominant religion of the Roman Empire. Behind Greco-Roman civilization lay Semitic languages, and there were translations of scripture into Coptic and Gothic, as well as Syriac.
Primarily, though, the story is just a bilingual one. This has ordinarily been perceived as unidirectional - from Greek to Latin. Fisher, Elizabeth A., "Greek translations of Latin literature in the fourth century A.D." in Yale Classical Studies 27 (1982): 173-215, however, shows that translation in the reverse direction was also important.
Drawing on Fisher, I discuss a Greek translation of Vergil, Eclogue 4. This translation is sometimes overtly Christian in its phrasing and even its syntax. Another, complementary point in the translator's agenda was an adaptation of Homeric and other traditions, whereby he could imply that his version somehow transcended Vergil. In line 26, for example, the Latin poet's single word parentis "of a parent" becomes the noun-adjective phrase patros te megistou "and of the greatest father", adapting a phrase used of Zeus at Homer, Iliad 3.276.
There is also a broader, Indo-European dimension. Besides the Homeric resonance, the translator's phrase "greatest father" is also paralleled in Avestan, at Yasht 17.16. In line 19, the replacement of Vergil's "ivy, with cyclamen" by the more tightly knit phrase "barley and galingale" results in a good example of what Watkins, How to Kill a Dragon, p. 45, in discussing phrases such as Hittite "barley and spelt", calls an Indo-European "merism". Still another part of the Indo-European dossier is the translator's combination in line 27 of huperenorieisi "superhuman feats" with kekasmenos "endowed with", paralleling the Vedic phrase narasamsa, used of Agni as a divine mediator.
Of course, the Greek translator did not know Avestan, Hittite, or Sanskrit - let alone Proto-Indo-European. There is not, however, anything unduly mysterious in the claim that he superimposes very ancient elements on Vergil's Latin. Basically, he will have been mining his own Greek tradition for patterns which we can now more readily observe outside of Greek.
Particularly important in this regard is the 7th century B.C. Epic Cycle. To judge from the few fragments still available, these poems were highly traditional in their use of poetic locutions; in fact, they sometimes seem more archaic than Homer. From such material (still extant in the fourth century A.D.), the translator would have had quite enough to draw on, as he sought to give his treatment of Eclogue 4 a sense of transcending the limitations under which, supposedly, Vergil himself had worked.