Why was Paul Klee’s first public exhibition in 1906 unsuccessful?

Paul Klee’s first public exhibition in 1906, which featured his series of etchings titled Inventions, was unsuccessful because it was largely ignored by the public.1

Furthermore, the caricatures that Klee produced during this period were rejected by critics and the public as being too idiosyncratic. Following this initial lack of professional recognition, Klee struggled to establish himself as an artist and had to rely on other means to earn a living, such as writing reviews of art exhibits and concerts, teaching life-drawing classes, and providing illustrations for books and journals.1