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,
Georges Braque throughout Paris and then Europe. The two artists' productive collaboration continued and they worked closely together until the beginning of World War I in 1914, when Braque enlisted with the French Army. In May 1915, Braque received a severe head injury in battle at Carency and suffered temporary blindness. He was trepanned, and required a long period of recuperation. Braque resumed painting in late 1916. Working alone, he began to moderate the harsh abstraction of cubism. He developed a more personal style characterized by brilliant color, textured surfaces, and—after his relocation to the Normandy seacoast—the reappearance of the human figure.