This "orloge de mer" or "heures de naviguer" was sent to him, as a gift, when he was still only a prince (being, therefore, before 1356 when he took the place of his father in prison), by John the hunter, through his aunt Yolanda de Aragón, when Juan asked him for a manuscript by Joan de Mandeville, "to translate it into the Aragonese language". This point is essential to know the language of the original, since it does not tell you " "to translate it into the Catalan language" ", which was the most important because it was yours - implying that you did not need any translation - on the other hand, if you had in Catalonia a copy in the Catalan language would not have been requested by her aunt, ergo the Yolanda de Aragón manuscript was in Catalan.