Cubism Cubism", (from 1909 to 1914) during which time Juan Gris emerged as an important exponent (after 1911); and finally Cooper referred to "Late Cubism" (from 1914 to 1921) as the last phase of Cubism as a radical avant-garde movement. Douglas Cooper's restrictive use of these terms to distinguish the work of Braque, Picasso, Gris (from 1911) and Léger (to a lesser extent) implied an intentional value judgement. Cubism burgeoned between 1907 and 1911. Pablo Picasso's 1907 painting "Les Demoiselles d'Avignon" has often been considered a proto-Cubist work. Georges Braque's 1908 "Houses at L’Estaque" (and related works) prompted the critic Louis
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