Despite occasional theoretical diversity, the actual practice of translation has hardly changed since antiquity. Except for some extreme metaphrasers in the early Christian period and the Middle Ages, and adapters in various periods (especially pre-Classical Rome, and the 18th century), translators have generally shown prudent flexibility in seeking equivalents — "literal" where possible, paraphrastic where necessary — for the original meaning and other crucial "values" (e.g., style, verse form, concordance with musical accompaniment or, in films, with speech articulatory movements) as determined from context.