This episode of By Design, presented with Bang & Olufsen, celebrates 100 years of De Stijl. The avant-garde movement founded by Piet Mondrian and Theo van Doesburg reduces abstraction to its most basic tenets: line, form and color. Join Julian Dawes as he traces the history and far-reaching influence of the movement and one of its most defining objects. Iconoplastic: 100 Years of De Stijl, 18 October – 8 December, New York.