We meet symmetry everywhere: in the cycle of the seasons, in the two-sided symmetry of the human face, but just as much in the 4-stroke motor, in the decimal expansion of the fraction 1/7, and in carpet patterns, ornaments, poems, and songs. Science, art, and modern production methods are based, in a far-reaching way, on symmetric forms and structures. In this book numerous examples of symmetry are presented in accessible form. The author who has also written in the same series, the book The Golden Section, contributes here to "sharpening the eye" of the reader for recognizing symmetry all around us and for appreciating its essential role as a methodological tool. This English edition has been prepared, with the author's cooperation, to make it available to English-speaking students of mathematics. The treatment is informal and the text is enriched by the presence of very illuminating diagrams. Questions are posed at fairly frequent intervals and the answers to these questions appear at the end of each chapter.