Art, Vision, and Symmetry: The Hidden Geometry of Frank Lloyd WrightFrank Lloyd Wright confronted us with two challenges when he wrote of his buildings that certain "basic principles behind the effects" "give to them all such vitality, integrity, and magic as they have." The first challenge: to uncover these principles; and, the second, to explain how they yield works of such aesthetic range and power. He gave us the first clue each building emerges from "the differentiation of a single, certain, simple form"; but he