The following text is an interview with René Berthier conducted in several times, between April and May 2018 by monde-nouveau.net, on the occasion of the bicentenary of Karl Marx’s birth. It was published on the online edition of Le Monde Libertaire, the journal of the Fédération anarchiste. For a better understanding of the subjects that were discussed and in order to clarify or supplement the information or opinions expressed, we have deemed it necessary to add notes. These notes are placed at the end of the text.