A well known Italian proverb, meaning roughly that a translator is a traitor.
Roughly being the basis of the problem. When doing a translation, the translator is faced with many difficulties. The most basic is laziness - he doesn't try his hardest to translate to the best of his possibilities. In that case he is obviously a traitor, both to the reader and to the original author.
But then, even if he cares about the translation, what path shall he take? He can try the most literal of translation; one that preserves meaning; or one that preserves the aesthetic experience of the texts. The translator will have to choose, because the preservation of all three will be impossible, yet, all three make a work of literature. For example, Traduttore taditore is highly assonant, more so than "a translator is a traitor". Preserving meaning can be quite as hard : in any text of some complexity, cultural references will abound. Shall he keep them, hoping the reader will understand? Shall he explain them? Shall he try to transfer them to the cultural framework of the target language?
Languages are vastly different. The terse prose of James Ellroy is too condensed to be rendered into French. It is impossible to fully render the original style in the target language. The translator will have to try and create another style, adapted to the new language. Indeed, when you read a translated work, it is at least as much the work of the translator as that of the author. The translator thus betrays the reader, who hoped to read a book by the original author, and the author himself, whose name is usurped.
Of course, it could simply mean that, given his attachment to two languages and thus to two countries, and their access to highly important information in need of translation, traitors are easy to recruit among translators and interprets. Given the Machiaviellian nature of Italian politics, where this proverb originated, it seems all too likely.
Apparently, Stalin had the habit of regularly sending his interpreters to the Gulag after they had assisted to one too many meetings. One is never too careful.
I always thought we should be careful about some people