According to one art historian, there were three phases of Cubism. There was "Early Cubism", (from 1906 to 1908) when the movement was initially developed by Picasso and Braque. In the second phase, "High Cubism", (from 1909 to 1914), Juan Gris emerged as an important exponent after 1911. Finally "Late Cubism" (from 1914 to 1921) was the last phase of Cubism as a radical avant-garde movement. Douglas Cooper's emphasis on the work of Braque, Picasso, Gris (from 1911) and Léger (to a lesser extent) was an intentional value judgement.