Three epigrams to put translation firmly in its place. English: “Poetry is what is lost in translation.’’ French: “If beautiful, not faithful; if faithful, not beautiful.’’ Italian with its play on words: “Traduttore, tradittore’’ (translator, traitor). David Bellos, wittiest and most ingenious of translators, has gone to war against such phrases. “Is That a Fish in Your Ear?’’ (the title promises some beautiful absurdity; rather disappointingly, it’s only the nickname given to the earphones that simultaneous translators wear), is an extended, passionate and detailed account of what translation does and how it does it.