Max Ernst (2 April 1891 – 1 April 1976) was a German (naturalised American in 1948 and French in 1958) painter, sculptor, graphic artist, and poet. A prolific artist, Ernst was a primary pioneer of the Dada movement and surrealism. He had no formal artistic training, but his experimental attitude toward the making of art resulted in his invention of frottage—a technique that uses pencil rubbings of objects as a source of images—and grattage, an analogous technique in which paint is scraped across canvas to reveal the imprints of the objects placed beneath. He is also noted for his novels consisting of collages.
Ernst Ludwig Kirchner (6 May 1880 – 15 June 1938) was a German expressionist painter and printmaker and one of the founders of the artists group Die Brücke or "The Bridge", a key group leading to the foundation of Expressionism in 20th-century art. He volunteered for army service in the First World War, but soon suffered a breakdown and was discharged. His work was branded as "degenerate" by the Nazis in 1933, and in 1937 more than 600 of his works were sold or destroyed.