Along with Diego Rivera (1886–1957) and Jose Clemente Orozco (1883–1949), Siqueiros was one of Mexico's three great muralists. Together, these painters laid the foundation for modern Mexican art during the 1920s. Believing that art should be made for the betterment of society and not for the private pleasure of the elite, they created large-scale, easily understood murals for public buildings. These images effectively communicated the plight of peasants and laborers during this turbulent time in Mexican history. For Siqueiros, a zealous political activist and member of the Communist Party of Mexico, painting was inseparable from politics. He worked on his first murals at Mexico's National Preparatory School from 1922 to 1924, but his dedication to politics was so great that at one time he set aside his artistic ambitions to work as a labor union organizer. He was a veteran of two civil wars and on several occasions was imprisoned, as well as exiled, for his activities and beliefs. While serving time in jail, the artist immersed himself in painting small-scale works, experiencing some of the most prolific periods of his career. During the 1930s, Siqueiros found a haven in New York and opened the Siqueiros Experimental Workshop, which was attended by the young American painter Jackson Pollock (1912–1956). In his teaching, Siqueiros emphasized the use of photography as an aid in developing compositions. He also advocated the employment of industrial materials and tools such as the spray-gun. He was a firm believer that modern technology should be used to create a new art for the times. During the early 1950s, Siqueiros expanded his themes of a utopian socialist society to include the progress of science and technology in the modern world. Throughout his career, the bold colors of industrial enamels, the dynamic lines of his compositions, and the portrayal of strong emotion infused all his works, regardless of scale or purpose, with movement and power.