Paul Klee (1879-1940) was born in Münchenbuchsee in Switzerland, the second child of Hans Klee, a German music teacher, and a Swiss mother. In 1880 the family moved to Bern. His training as a painter began in 1898 when he studied drawing and painting in Munich for three years. By 1911 he became involved with the German Expressionist group Der Blaue Reiter (The Blue Riders), founded by Wassily Kandinsky and Franz Marc in 1911. Klee and Kandinsky became lifelong friends. His work was also influenced by the Cubism of Pablo Picasso and Georges Braque and the abstract translucent colour planes of Robert Delaunay. In 1914, Klee visited Tunisia. The experience was the turning point in his life and career. The limpid light of North Africa awakened his sense of colour. During his stay, Klee gradually detached colour from physical description and used it independently, which gave him the final needed push toward abstraction. In 1920 Walter Gropius invited Klee to join the faculty of the Bauhaus in Weimar. A school of architecture and industrial design, it also included the study of arts and crafts. Nearly half of Klee's 10,000 works were produced during the ten years he taught at the Bauhaus. When the National Socialists declared his art degenerate in 1933, Klee returned to his native Bern. Personal hardship and the increasing gravity of the political situation in Europe are reflected in the sombre tone of his late work.