De Stijl: The Geometric Ornament and Monumental Design deals with the theoretical and formal foundations for the collaboration of painters, architects, and designers in the artist group De Stijl (1917-1931). Like the Bauhaus or Russian Constructivism, De Stijl represents an attempt by the European avant-garde to unify the arts based on a modern vocabulary of forms. The roots of this project lie in the style discussions of the 19th century, focusing on the theory and practice of the decorative. This can be illustrated through various concepts that connect De Stijl with the aesthetic discourse of the turn of the century: the straight line, geometric ornament, monumental art, and spatial art. The conceptual tension on which De Stijl was built likely also contributed to the end of the style project. The artistic collaboration at the intersection of applied and fine arts proved to be so difficult and unstable that it ultimately could not withstand the opposing developments and shifts in values.