Paul Klee was a Swiss-born German artist. His highly individual style was influenced by movements in art that included expressionism, cubism, and surrealism. Klee was a natural draftsman who experimented with and eventually deeply explored color theory, writing about it extensively; his lectures Writings on Form and Design Theory (Schriften zur Form und Gestaltungslehre), published in English as the Paul Klee Notebooks, are held to be as important for modern art as Leonardo da Vinci’s A Treatise on Painting for the Renaissance. He and his colleague, Russian painter Wassily Kandinsky, both taught at the Bauhaus school of art, design and architecture in Germany. His works reflect his dry humor and his sometimes childlike perspective, his personal moods and beliefs, and his musicality. Klee’s artistic legacy has been immense, even if many of his successors have not referenced his work openly as an apparent source or influence. During his lifetime, the Surrealists found Klee’s seemingly random juxtaposition of text, abstract signs, and reductive symbols suggestive of the way the mind in dream state recombines disparate objects of everyday and thus brings forth new insights into how the unconscious wields power even over waking reality. In European art after the 1940s, artists such as Jean Dubuffet continued to reference the art of children as a kind of untutored, expressive ideal. Klee’s reputation grew considerably in the 1950s, by which time, for instance, the Abstract Expressionists could view his work in New York exhibitions. Klee’s use of signs and symbols particularly interested the artists of the New York School, especially those interested in mythology, the unconscious, and primitivism (as well as the art of the self-trained and that of children). Klee’s use of color as an expressive medium of human emotion in its own right also appealed to the Color Field painters, such as Jules Olitski and Helen Frankenthaler. Finally, American artists maturing in the 1960s and 1970s, such as Ellsworth Kelly owed a debt to Klee for his pioneering color theory during the Bauhaus period.