1922, he attended the International Congress of Progressive Artists and signed the "Founding Proclamation of the Union of Progressive International Artists". Kandinsky taught the basic design class for beginners and the course on advanced theory at the Bauhaus; he also conducted painting classes and a workshop in which he augmented his colour theory with new elements of form psychology. The development of his works on forms study, particularly on points and line forms, led to the publication of his second theoretical book (Point and Line to Plane) in 1926. His examinations of the effects of forces on straight lines, leading to the contrasting tones of curved and angled lines, coincided with the research of Gestalt psychologists, whose work was also discussed at the Bauhaus. Geometrical elements took on increasing importance in both his teaching and painting—particularly the circle, half-circle, the angle, straight lines and curves. This period was intensely productive. This freedom is characterised in his works by the treatment of planes rich in colours and gradations—as in Yellow – red – blue (1925), where Kandinsky illustrates his distance from the constructivism and suprematism movements influential at the time. The Yellow – red – blue (1925) of several main forms: a vertical yellow rectangle, an inclined red cross and a large dark blue circle; a multitude of straight (or sinuous) black lines, circular arcs, monochromatic circles and scattered, coloured checker-boards contribute to its delicate complexity. This simple visual identification of forms and the main coloured masses present on the canvas is only a first approach to the inner reality of the work, whose appreciation necessitates deeper observation—not only of forms and colours involved in the painting but their relationship, their absolute and relative positions on the canvas and their harmony. Kandinsky was one of Die Blaue Vier (Blue Four), formed in 1923 with Paul Klee, Lyonel Feininger and Alexej von Jawlensky, which lectured and exhibited in the United States in 1924. Due to right-wing hostility, the Bauhaus left Weimar and settled in Dessau in 1925. Following a Nazi smear campaign the Bauhaus left Dessau in 1932 for Berlin, until its dissolution in July 1933. Kandinsky then left Germany, settling in Paris. Great Synthesis (1934–1944) Living in an apartment in Paris, Kandinsky created his work in a living-room studio. Biomorphic forms with supple, non-geometric outlines appear in his paintings—forms which suggest microscopic organisms but express the artist's inner life. Kandinsky used