Jean Metzinger see the cubist works in Room 7 and 8. While Pablo Picasso and Georges Braque are generally acknowledged as the founders of the twentieth-century movement that became known as Cubism, it was Jean Metzinger, together with Albert Gleizes, that created the first major treatise on the new art-form, "Du "Cubisme"", in preparation for the Salon de la Section d'Or held in October 1912. "Du "Cubisme"", published the same year by Eugène Figuière in Paris, represented the first theoretical interpretation, elucidation and justification of Cubism, and was endorsed by both Picasso and Braque. "Du "Cubisme"", which preceded Apollinaire's well known essays,
20th-century Western painting for that spiritual knowledge. Other major pioneers of early abstraction include Swedish painter Hilma af Klint, Russian painter Kazimir Malevich, and Swiss painter Paul Klee. Robert Delaunay was a French artist who is associated with Orphism, (reminiscent of a link between pure abstraction and cubism). His later works were more abstract, reminiscent of Paul Klee. His key contributions to abstract painting refer to his bold use of color, and a clear love of experimentation of both depth and tone. At the invitation of Kandinsky, Delaunay and his wife the artist Sonia Delaunay, joined The Blue Rider (Der Blaue Reiter), a