“From Letter to Ludwig Büchner (in Darmstadt), Hanover, May 1, 1867. Dear Sir: (…) I consider it of the highest importance to free in French from the false views in which Proudhon, with his idealized petty-bourgeoisness, has buried them. At the Geneva Congress, as well as in the connections that I, as a member of the General Council of the International Working Men’s Association, have had with the French Branch, I have repeatedly encountered the most repulsive consequences of Proudhonism. (…)”. Faithfully yours, Karl Marx” [Karl Marx, On the First International, a cura di Saul K. Padover, 1972]