“Poetry is what gets lost in translation,” observed Robert Frost, and was only partly right. The thrust and sweep of epic poetry translates well enough: there is no dearth of decent translations of Homer, Virgil, Dante. Philosophical poetry also survives quite well: Eliot’s Four Quartets, for example, has been successfully rendered into a number of languages. Lyric poetry is the one that has the most to lose.
There is, obviously, the problem of rhyme. Unrhymed poetry fares much better in translation: Walt Whitman reads just about as well (or poorly) in French or German. Even as delicate an unrhymed lyric as Leopardi’s “L’infinito” has thrived in English. But rhyme is a killer. With elaborate rhyme schemes, tricky rhyming words, and short lines (dimeter, trimeter), the difficulty increases exponentially. Think of Byron’s Don Juan, or this, from Heine: “Sie sassen und tranken am Teetisch,/ Und sprachen von Liebe viel./ Die Herren, die waren ästhetisch,/ Die Damen von zartem Gefühl.” Verses 2 and 4, with their masculine rhymes, are no problem: “And talked about love and such” and “The ladies who felt so much.” But 1 and 3 are impossible: the splendid joke lies in rhyming, femininely at that, Teetisch and ästhetisch, “tea table” and “aesthetic.” Failing this, you’ve got nothing.
But there are poems untranslatable not because of their intricate rhyme scheme, rich rhymes, or fancy prosody. There exists something even more basic. In my doctoral dissertation, I quote from the journal of Jules Barbey