Proto-Cubism that Metzinger was the first to recognize explicitly and implicitly the significance of the use of "a free, mobile perspective", and the "mixing... of the successive and the simultaneous". He was the first to write of the fact that artists had abandoned traditional perspective and were now free to move around their subjects to paint them from various points in space, and at various moments in time. Metzinger's role at center of Cubism both as a painter and theorist prompted Guillaume Apollinaire to write of Picasso, Braque and Metzinger as the first three Cubist painters. Now well beyond the teachings
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.