ABSTRACTThe aim of this article is twofold: first, to show that, in Plato'sHippias Major,Hippias is the mouthpiece of a materialist ontology; second, to discuss the critique of this ontology. My argument is based on an interpretation ofHippias Major300b4–301e3. I begin by revealing the shortcomings of P. Woodruff's and I. Ludlam's interpretations. Next, I define the concept of materialism as it was understood in ancient Greece in order to outline the specificity of Hippias' materialism. Finally, I argue that the opposition between (...) the two characters of theHippias Majorrepresents in fact an ontological opposition between two conceptions of what a unity is, i.e., Hippias' elementary corporal unities and Socrates' “formal unity.”. (shrink)