Abstract art based on Cézanne's idea that all depiction of nature can be reduced to three solids: cube, sphere and cone. With the painting "Les Demoiselles d'Avignon" (1907), Picasso dramatically created a new and radical picture depicting a raw and primitive brothel scene with five prostitutes, violently painted women, reminiscent of African tribal masks and his own new Cubist inventions. Analytic cubism was jointly developed by Pablo Picasso and Georges Braque, from about 1908 through 1912. Analytic cubism, the first clear manifestation of cubism, was followed by Synthetic cubism, practiced by Braque, Picasso, Fernand Léger, Juan Gris, Albert Gleizes, Marcel Duchamp and
Pablo Picasso by which time the artist had started to sign his work "Picasso"; before he had signed "Pablo Ruiz y Picasso". Picasso's Blue Period (1901–1904), characterized by sombre paintings rendered in shades of blue and blue-green, only occasionally warmed by other colours, began either in Spain in early 1901, or in Paris in the second half of the year. Many paintings of gaunt mothers with children date from the Blue Period, during which Picasso divided his time between Barcelona and Paris. In his austere use of colour and sometimes doleful subject matter – prostitutes and beggars are frequent subjects – Picasso