The Fairy Feller's Master-Stroke

Richard Dadd murdered his father in 1843, believing him to be the Devil. He spent the rest of his life in the criminal asylums of Bethlem and Broadmoor. He painted this canvas there over nine years with the fineness of a miniaturist. The central fairy is about to swing his axe to split a hazelnut — which the rest of the dense hallucinatory court has been waiting for. He never finished it. Now at Tate Britain, London @tate