Articles and lectures reflected his polemical, combative ideals and points of view. In “Siqueiros y el arte de masas”, published in Buenos Aires’ Nueva Revista, Berni put across his differences with the Mexican artist about the limits of mural art. He criticized the experience of Ejercicio Plástico stating,

Mural painting cannot be but one of the many forms of popular expression. Wanting to make the muralist movement the battle horse of masses art in the bourgeois society is to condemn this movement whether to passiveness or to opportunism. In its progressive fascistization, the bourgeoisie will not give out its monopolized walls for proletarian ends [...] The most concrete evidence of this in Buenos Aires we have it with Siqueiros [...] The pretext to make a technical experience cannot justify the void of contents. To perform a mural painting Siqueiros had to get hold of the first board the bourgeoisie offered him.

He also made known, through the press in Rosario, the initiative he headed from the Mutualidad to create a fine arts academy in that town, thus opposing public opinions contrary to the project.

Helped by Anselmo Piccoli he realized the closest work to Mexican muralism, El hombre herido. Documentos fotográficos, a pyroxylin air blowpipe painted panel, today missing. It