Paul Klee developed a complex repertoire of symbols starting in 1912/13, which he continued to use until his death. Several of his statements suggest that these symbols were intended to provide viewers access to the contents of his works that could no longer be understood rationally. However, Klee kept them secret throughout his life. Can this contradiction be resolved? Interpreters recognized only some of the figurative motifs as symbols, overlooking the abstract line and surface forms, colors, and work numbers. The author deciphered these through years of meticulous detective work. Her research findings culminated in this book, which reinterprets or redefines numerous works by Klee, offering deep insights into the creative process.