"Always judge a book by its cover" - about the cover design of books. In today's publishing and bookselling world, the cover holds special significance: as a graphic surface that we encounter in publishing announcements, advertisements, book reviews, and bookstore displays, it is meant to spark curiosity, promote the book, provide information about the content, author, and publisher, and ideally be visually appealing and well-designed. A cover also creates a visual connection between the author and the publisher and serves as the publisher's business card. The typographer and designer Klaus Detjen, who was awarded the Gutenberg Prize in 2017, examines the development of book design in Germany and its outstanding figures in four sections: from the beginning of book covers at the end of the 19th century to the early modern period of the 1920s.