Discusses the various ways in which different languages are used in British (mainly English) manuscripts, 10th to 15th centuries, emphasizing fluidity across modern linguistic boundaries and the essentially comparative nature of literacy in a context where there were no literate monoglots. One section builds on theories of diglossia to address how a language might at times be presented as a prestigious 'book language' and at others as a 'non-book language' accessing different kinds of affectivity and experience. Another discusses how medieval knowledge was 'found in translation', such that transmission between languages was foundational to knowledge discourses. According to the Fédération Internationale des Traducteurs, the Middle Ages was a Golden Age when translators could ‘omit passages and insert commentaries to an extent never again equalled in the history of translation in the West’.