The double-functioning element has been used infrequentlyin Modern architecture. Instead, Modern architecture has encouraged separation and specialization at all scales-in materials and structure as well as program and space. "The nature of materials" has precluded the multifunctioning
material, or, inversely, the same form or surface for different materials. Wright's divergence from his master began, according to his autobiography, with Louis Sulli- van's indiscriminate application of his