Did Numenius comment on the Parmenides ? If, as a Platonist of his time, Numenius used the Timaeus and the Politeia both to elaborate and support his thoughts on Metaphysics and Cosmology, it is now usual to think that he also used the Parmenides in his description of the first principle and it could be tempting to believe that by doing so he identified this first principle with the One. However, on close examination, his work gives but few clues to bear out such a possibility. In spite of these conclusions, the hypothesis subsists for reasons that depend essentially on the History of Philosophy and on the researches it produces. It is indeed often taken up again for three reasons, presented as corollaries: the status of Numenius himself as a Pythagorean Platonist, a predecessor of Plotinus; the real affinities between his thought and the doctrine of The Anonymous Commentary on the Parmenides; the parallels also seen between his phrases and the ones from the supposedly common source to the Zostrianus and the Against Arius by Marius Victorinus, a source presented as really close to the Anonymous Commentary. In other words, the three reasons put forward originate less in the study of Numenius’ work itself than in the research on the sources of other texts whose authors and origins are not well defined, a research based partly on the links of this work with its supposed “peers” in Pythagoreanism. Third part: Reconsidering the sources of the “exposé commun” (Numenius, The Anonymous Commentary on the Parmenides, the Zostrianus and Marius Victorinus) This third part of the study presents the last episode of the research on the potential relation between Numenius and the Parmenides. The first part has shown that Numenius’ transmitted work does not bear any trace of the use of this dialogue in the elaboration of the doctrine about the first two principles; the second part has tried to prove that Numenius, in all likelihood, is not the author of The Anonymous Commentary on the Parmenides. The paper deals here with what Michel Tardieu (1996) called “l’exposé commun”, the discourse common to the Zostrianus and the Against Arius by Marius Victorinus. The obvious parallels between this discourse and The Anonymous Commentary on the Parmenides and also with some phrases by Numenius suggested that the latter was its source, a view sometimes used to support the hypothesis that he really was after all the author of the Commentary. Here again, the detailed examination of the texts and their confrontation reveal the weakness of this double conclusion. Re-examining the source of the discourse, in reality partly common to the Coptic Zostrianus and Marius Victorinus, shows however that Numenius has certainly been used for its elaboration and that he could consequently have been used as a source by the Gnostics, as well as by the Neoplatonists, and thus sometimes, indirectly or a contrario, for their interpretation of the Parmenides.