This article will examine some theses that Badiou developed in the first period of his philosophy, when he was close to the theoretical horizon of Althusserianism. The article traces a route back from the Manifesto for Philosophy to some yet unpublished notes, dating from the late Sixties, on an aborted collective project on materialist philosophy. While, according to the later Badiou – who is also the most well-known – contemporary philosophical discourse should recover the Platonic gesture after Heidegger, it will be shown that the early Badiou, by debating the nature of the Platonic gesture with Macherey, seems to conceptualise philosophical discourse and its function under the inseparable link of dialectical materialism and historical materialism. The article ends with some open questions for a possible theory of discourse that would build on Badiou’s theoretical insights.