Paul Klee's lifelong engagement with the possibilities of colour and abstraction made him a key figure in the development of modernism. Influenced by Cubism, Expressionism and Surrealism, Klee's own work was varied and experimental. After joining the German group Der Blaue Reiter (The Blue Rider), Klee fought in the First World War before emerging as one of the leading artists in Germany. He taught at the world-famous Bauhaus school of art for...