This fascinating study explores a fundamental paradox behind the patterns of the natural world, in which symmetrical causes lead to asymmetrical effects. Lesser and greater patterns—the structure of subatomic particles, a tiger's stripes, the shapes of clouds, and the vibrations of the stars—are produced by broken symmetry. This accessible exploration of the physical and biological world employs the mathematical concepts of symmetry to consider the deepest questions of modern physics. An active popularizer of mathematics, Ian Stewart is a university professor and former columnist for Scientific American's "Mathematical Games" column. Martin Golubitsky is Distinguished Professor of Mathematics and Physical Sciences at the Ohio State University, where he serves as Director of the Mathematical Biosciences Institute. Both authors share an interest in the application of new mathematical ideas to scientific problems. More than 120 figures illustrate their illuminating survey of the interaction of symmetry with dynamics and the mathematical unity of nature's patterns.