Translating poetry is difficult for a number of reasons. There are a few different threads which, when you translate, you take in one hand and try to master simultaneously. First, there is meaning. Yes, attempts at literal translation of the entire work may be futile, but some words, some phrases, are so rich in meaning, and so precise in expressing that meaning, that we feel that none of it should be lost by translation. Take Kavanagh’s “the spirit-shocking wonder in a black slanting Ulster hill”, or Severyanin’s “вхожу в столичную тоску”, for example. Faced with words so rich in meaning and weighty with expression, we have two choices: try to squeeze the meaning out of each word and assemble the results; or sidestep them with a metaphor. Severyanin’s words above, for example, I have translated as “I melt into the madding crowd”, which dispenses, unfortunately, with the aches and pangs of suffering in the Russian "тоска", now merely fossilised in the English ‘madding’.
That is, probably, but one aspect of “meaning”. In general, however, one can say that here, as everywhere in translation, sacrifices must be made, but, as opposed to non-fiction, meaning is oftener sacrificed to style, and not the other way round.
Next, problems arise with rhyme and metre. With rhyme we must make a basic decision: whether the translation should rhyme. A positive answer complicates things, but does give us a framework within which to work, and, in a way, a guide. This choice may be influenced by the presence of rhyme in the original.
Regardless of whether our translation rhymes, some sort of internal rhythm is likely to prevail. The reproduction of this or a similar rhythm in the translation is determined by our choice of sounds, both vowel and consonantal, and of words with the necessary stress.
Even, taking just ‘meaning’, ‘rhyme’ and ‘rhythm’ – and the problems of translating poetry don’t end there – we can see that the essence of translating poetry lies in the successful mastery of all of these: having found an exact word for "стрёмный" in English, we must make it fit both the rhyme and rhythm, as well as, if all goes well, achieving the elusive aim of having the translation “sound” and produce the same effect as it would in the original.