The paper deals with the theme of memory Islamic in medieval culture, and with its persistence and its transition from being a moral virtue to a specific part of the brain. Along this transition, different epistemological approaches have measured the new extents of "what’s to be known" and "how to know". The authors here engaged in a transit of texts and contexts (as well as in discussions inherited from the past and projected into “modern” perspectives) are ps. Ibn al-Muqaffa‘, the theologian 'Abd al-Jabbar, Rufus of Ephesus, al-Farabi, Nemesius of Emesa, up to the “science-fiction” of ps. Jabir ibn Hayyan and his artificial creature whose brain must learn to know.