Happy birthday to Max Ernst, born on this day in 1891. As one of the founders of the dada and surrealist movements the German-born artist completely reconceived the nature of art, combining sculpture, collage, painting and poetry with new forms of art production, including “frottage” (creating rubbings from textured materials) and automatic writing. The latter forms the basis of the Sammlung Scharf-Gerstenberg’s exhibition Max Ernst, Stealer of Marks (until 28 April), which examines his preoccupation with cryptographic writing, the influence of Egyptian hieroglyphics, and an obsession with disguising hidden messages within his work.