The notion of author seems to be of little relevance in the world of medieval writing, dominated by the imaginary of auctoritas. This article aims to describe the complex relationship of the medieval writer to the written word and the various enunciative positions that result from it, according to a certain hierarchy. It thus proposes to reflect on the way in which Alfonso X, as king, invested the authority of writing in order to elaborate a historiographic discourse in accordance with his political project, thus drawing a place for an “authorship”.