This paper investigates the problems of transferring scientific literature from one culture to another, in this case, with respect to the translation of texts from Arabic into Latin in the sixth-seventh centuries AH/twelfth-thirteenth centuries AD. It takes as its starting point the injunction of Ibn ʿAbdūn to the market-traders of Seville in the early sixth/twelfth century that they “should not sell to the Jews or Christians books concerning science . . . [because] they translate them and attribute them to their co-religionists and their bishops” and investigates whether Christian translators made the translations against the will of Islamic authorities, disguised the translations’ Arabic origin to pass off the works as their own and dishonoured Islam in their treatment of Arabic books. Only in the last case is there some evidence of practices that may give grounds for Ibn ʿAbdūn’s prohibition.