Paul Klee's theory of form and design is published here for the first time in its entirety, covering the elementary, content-related, and stylistic areas. From the wealth of his notes and the organizational methods of his thinking, a new access to his artistic work emerges, transcending any interpretation. Alongside the written theoretical explanations and his image analyses, an additional element of clarification is introduced: the text is accompanied by drawings that illustrate the connections. From simple forms to the complex interconnections of image elements, movement is at the center of his form thinking. The optical foundations of his theory of form presented here are impressively organized as a guide into the world of his images.