1914 and 1916 was signaled by a shift towards a strong emphasis on large overlapping geometric planes and flat surface activity. This grouping of styles of painting and sculpture, especially significant between 1917 and 1920, was practiced by several artists; particularly those under contract with the art dealer and collector Léonce Rosenberg. The tightening of the compositions, the clarity and sense of order reflected in these works, led to its being referred to by the critic Maurice Raynal as 'crystal' Cubism. Considerations manifested by Cubists prior to the outset of World War I—such as the fourth dimension, dynamism of modern life, the occult, and Henri Bergson's concept of duration—had now been vacated, replaced by a purely formal frame of reference. Crystal Cubism, and its associative rappel à l'ordre, has been linked with an inclination—by those who served the armed forces and by those who remained in the civilian sector—to escape the realities of the Great War, both during and directly following the conflict. The purifying of Cubism from 1914 through the mid-1920s, with its cohesive unity and voluntary constraints, has been linked to a much broader ideological transformation towards conservatism in both French society and French culture. Cubism after 1918 The most innovative period of Cubism was before 1914. After World War I, with the support given by the dealer Léonce Rosenberg, Cubism returned as a central issue for artists, and continued as such until the mid-1920s when its avant-garde status was rendered questionable by the emergence of geometric abstraction and Surrealism in Paris. Many Cubists, including Picasso, Braque, Gris, Léger, Gleizes, and Metzinger, while developing other styles, returned periodically to Cubism, even well after 1925. Cubism reemerged during the 1920s and the 1930s in the work of the American Stuart Davis and the Englishman Ben Nicholson. In France, however, Cubism experienced a decline beginning in about 1925. Léonce Rosenberg exhibited not only the artists stranded by Kahnweiler's exile but others including Laurens, Lipchitz, Metzinger, Gleizes, Csaky, Herbin and Severini. In 1918 Rosenberg presented a series of Cubist exhibitions at his Galerie de l’Effort Moderne in Paris. Attempts were made by Louis Vauxcelles to argue that Cubism was dead, but these exhibitions, along with a well-organized Cubist show at the 1920 Salon des Indépendants and a revival of the Salon de la Section d’Or in the same year, demonstrated it was still alive. The reemergence of Cubism coincided with the