"This book tells the story of the pentagon and its cousin, the pentagram, delving into the shapes' history, mathematical features, cultural significance, and their role in nature, science, and art. While the pentagon may seem to be a quotidian shape, it has a fascinating history. It was a favorite symbol of the Pythagoreans, a cult who reportedly used the shape to identify themselves to other members. Over the years, it became a source of fascination for mathematicians, and efforts to study this shape ultimately led to the discovery of the golden ratio. In the late 1900s, a materials scientist discovered a material whose crystal structure displayed fivefold symmetry-breaking a core tenet of chemical symmetry. Despite its rich history, the pentagon has not yet received a book-length treatment. This book provides the first such treatment, offering a sweeping view of the five-sided polygon and its role in mathematics, history, nature, and art. The book discusses Fibonnacci numbers, stained-glass design, and pentagonal medieval fortifications, among other topics. Striking illustrations by artist Eugen Jost provide a visual representation of this object's history."