A prevalent idea among contemporary scholars is that Euclid belonged to, or was heavily influenced by the Platonic philosophical tradition. To a certain extent, this impression is not new; the quest for Euclid's philosophical background was probably triggered and enhanced by his late commentators, Greeks and Arabs, who appear confident that he had one. For instance, al-Qifti writes: 'Euclid...called the author of geometry, a philosopher of somewhat ancient date...' and al-Nadim in the Fihrist names Euclid as '...one of the mathematical philosophers...' Proclus, five centuries earlier than al-Nadim, was more specific: '[Euclid] was a follower of Plato by choice, and familiar with this philosophy'. In this paper, I propose to explore the extant accounts on Euclid's philosophical background. (Michalis Sialaros, University of London)