(b Cortona, 7 Apr. 1883; d Paris, 26 Feb. 1966). Italian painter, designer, and writer on art, active mainly in Paris. He first settled there in 1906, and he played an important role in transmitting the ideas of French avant-garde art to the Futurists, both of whose manifestos of painting he signed in 1910. His work was strongly influenced by Cubism (he knew Braque and Picasso) and he concerned himself with the problem of conveying a sense of movement and action by breaking up his picture space into contrasting and interacting rhythms (Suburban Train Arriving in Paris, 1915, Tate, London). He was influenced by theories of mathematical proportion and in 1921 published a book on the subject, Du Cubisme au classicisme. In the 1920s his style became more traditional and he carried out several decorative commissions, including murals for churches in Switzerland.