War, Severini gradually abandoned the Futurist style and painted in a synthetic Crystal Cubist style until 1920. By 1920 he was applying theories of classical balance based on the Golden Section to still lifes and figurative subjects from the traditional commedia dell'arte. He became part of the "return to order" in the arts in the post-war era. Works such as The Two Pulchinellas (1922) exemplify Severini's turn toward a more conservative, analytic type of painting, which nonetheless suggests metaphysical overtones. After 1920, Severini divided his time between Paris and Rome. In 1921, he was commissioned by George Sitwell to paint murals for Montefugoni castle, which the latter had bought in 1909; the same year, Severini published Du cubisme au classicisme: Esthétique du compas et du nombre, a book summarizing his research into mathematical theories of harmony and proportion. The murals were completed in 1922. In 1923 and 1925 he took part in the Rome Biennale. He exhibited in Milan with artists of the Novecento Italiano group in 1926 and 1929 and in their Geneva exhibition of 1929. From 1928 he began to incorporate elements of Rome's classical landscape in his work. In 1930 he took part in the Venice Biennale, exhibited in the Rome Quadrennials of 1931 and 1935, and in 1935 won the first prize for painting, with an entire room devoted to his work. He contributed a cycle of works to the Paris Exhibition. He explored fresco and mosaic techniques and executed murals in various media in Switzerland, France, and Italy. During this decade, he taught the Swiss printmaker Lill Tschudi, who had previously studied at the Grosvenor School of Modern Art. Later life In the 1940s Severini's style became semi-abstract. In the 1950s he returned to his Futurist subjects: dancers, light and movement. He executed commissions for the church of Saint-Pierre in Freiburg and inaugurated the Conségna delle Chiavi ("Delivery of the Keys") mosaic. His mosaics were shown at the Cahiers d'Art gallery in Paris and he participated in a conference on the history of mosaic at Ravenna. He received commissions to decorate the offices of KLM in Rome and Alitalia in Paris and took part in the exhibition The Futurists, Balla - Severini 1912–1918 at the Rose Fried Gallery in New York. In Rome he reconstructed his Pan Pan Dance mosaic, which had been destroyed in the war. He was awarded the Premio Nazionale di Pittura