Historians of philosophy often hesitate to assign Numenius to any one particular philosophical school. He is sometimes considered a Pythagorist, sometime a Platonist. Michael Frede seems to put an end to the controversy by calling him a “Pythagoreanising Platonist”. The paper deals with the question by examining the way in which Numenius sacralises Pythagoras and the polemical dimension of this sacralisation. To reach a Platonism that is really one and authentic, Numenius places Pythagoras at its origin, portrays Plato and even Socrates as his pupils, and excludes from this line of thought all that is foreign to his interpretation of Plato. In this way, he is in conflict with those who, on the contrary, have recourse to inclusion in order to reconstruct the unity of the Academy and thus accept other trends within it. If, from an historiographical point of view, Numenius is indisputably a Platonist, he probably saw himself as a Pythagorist.