In the 1920s, alongside works by Fernand Léger and Henri Laurens, a representative group of paintings by the Cubist Juan Gris, who had died young, entered the Rupf collection from Galerie Simon in Paris that had been newly founded by Kahnweiler in the wake of World War I. All this was significant also because Kahnweiler had called Gris a “pure classic” and, following his escape from Paris in 1940, he studied Gris intensively. It was during this perilous time that he authored an extensive monograph on Gris, which was published after the end of the war in 1946.

The painting by August Macke, which Rupf acquired in 1939 at the Lucerne auction Moderne Meister aus deutschen Museen (Modern Masters from German Museums), that is, “degenerate” art, likewise testifies to the threat posed by the Nazis.