very good knowledge of the language, written and spoken, from which they are translating (the source language); an excellent command of the language into which they are translating (the target language); familiarity with the subject matter of the text being translated; a profound understanding of the etymological and idiomatic correlates between the two languages, including sociolinguistic register when appropriate; and a finely tuned sense of when to metaphrase ("translate literally") and when to paraphrase, so as to assure true rather than spurious equivalents between the source and target language texts. A competent translator is not only bilingual but bicultural. A language is not merely a collection of words and of rules of grammar and syntax for generating sentences, but also a vast interconnecting system of connotations and cultural references whose mastery, writes linguist Mario Pei, "comes close to being a lifetime job."] The complexity of the translator's task cannot be overstated; one author suggests that becoming an accomplished translator—after having already acquired a good basic knowledge of both languages and cultures—may require a minimum of ten years' experience. Viewed in this light, it is a serious misconception to assume that a person who has fair fluency in two languages will, by virtue of that fact alone, be consistently competent to translate between them. Emily Wilson, a professor of classical studies at the University of Pennsylvania and herself a translator, writes: "[I]t is [hard] to produce a good literary translation. This is certainly true of translations of ancient Greek and Roman texts, but it is also true of literary translation in general: it is very difficult. Most readers of foreign languages are not translators; most writers are not translators. Translators have to read and write at the same time, as if always playing multiple instruments in a one-person band. And most one-person bands do not sound very good." The translator's role, in relation to the original text, has been compared to the roles of other interpretive artists, e.g., a musician or actor who interprets a work of musical or dramatic art. Translating, especially a text of any complexity (like other human activitiesinvolves interpretation: choices must be made, which implies interpretation.Mark Polizzotti writes: "A good translation offers not a reproduction of the work but an interpretation, a re-representation, just as the performance of a play or a sonata is a representation of the script or the score, one among many possible representations."[] A translation of a text of any complexity is – as, itself, a work of art – unique and unrepeatable.