The study of the contents of the manuscript Rep. I 30B of Leipzig University Library, a codex catalogued in the 19th century but almost ignored, provides new evidence of known translations into Spanish and of others hitherto unknown. In the first case we find Seneca’s translated or commissioned for translation by Fernán Pérez de Guzmán, several chapters of Tacitus’s and the according to the text by Pere Torroella. In the second, a new version (the second) of the false epistolary between Seneca and Saint Paul, a work that allowed Saint Jerome to introduce the Cordovan philosopher in his list of and an plot that even made some medieval authors think about the conversion of the old Seneca to Christianity. In order to reach these conclusions, a careful textual analysis is performed. An edition of this second translation of the apocryphal epistolary is included at the end of the article.