For many centuries, symmetry remained a key concept for artists, architects and musicians, but in the 20th century its deep meaning was also appreciated by physicists and mathematicians. It is symmetry that today underlies such fundamental physical and cosmological theories as relativity, quantum mechanics and string theory. From ancient Babylon to the cutting edge of modern science, Ian Stewart, a world-renowned British mathematician, traces the study of symmetry and the discovery of its fundamental laws. The eccentric Girolamo Cardano - a gambler and a bully of the Renaissance, the first to solve the cubic equation, the neurotic genius and failed revolutionary Evariste Galois, who single-handedly created group theory, the bitter drunkard William Hamilton, who scribbled his greatest discovery on the masonry of a bridge, and, of course, the great Albert Einstein - the fates of these extraordinary people and brilliant scientists serve as the spectacular backdrop against which one of the most exciting stories in the history of science unfolds.