Gli interventi autografi di Giorgio Gemisto Pletone nel codice matematico Marc. gr. Z 301

Two interventions in the mathematical ms. Marc. gr. Z 301 are for the rst time assigned to the hand of the renowned Renaissance philosopher George Gemistus Plethon. ese interventions are: a radical, and philosophically signi cant, modi - cation of the principles set out at the beginning of book I of Euclid’s Elements, and the transcription, in leaves le blank by the main copyist, of three short texts featur- ing a solution of the problem of the duplication of the cube, an original method of extraction of an approximate square root, and a short exposition on composition and removal of ratios. e modi cation of the principles of the Elements is thoroughly discussed, with special emphasis on its consequences on the rst printed editions of the Euclidean treatise. A critical edition, together with translation and commentary, of the three texts is provided, taking into account all of their manuscript witnesses.