Even before Gutenberg invented the printing press, books were being, written, painted and bound for hundreds of years. Books were made of stretched parchment and bound by sewing. The tradesmen of the middle ages, Coopers, Harpoon Makers, etc. are long gone but the Bookbinder is still around.
I just visited an exhibition at The Metropolitan Museum of Art: “The Art of Illumination: The Limbourg Brothers and the Belles Heures of Jean de France, Duc de Berry.” Books of the Hours were prayer books written and drawn for wealthy laymen. This is a fine example of just such a book. It is normally on Display at The Cloisters, a branch of The Metropolitan Museum of Art. At the Cloisters, the book is bound, here it is unbound so each page can be viewed.
Also being shown was a short film made by the Getty museum for their current exhibition “The Making of a Medieval Book.” It seems that the medieval bookbinder bound books much in the same way that hard cover book binders bind books today. Once the writing and illuminating had been completed, the parchment sheets were folded and nested into groups called gatherings. The gatherings were ordered in their proper sequence and sewn together onto cords or leather thongs that served as supports. These gatherings were the forerunner of the signature.
It was a marvelous show and the illuminations are strikingly well preserved. But if you can’t make it to New York, visit the Met’s web site to see what is in the exhibition: http://blog.metmuseum.org/artofillumination/about-the-exhibition/
Further explanation and a video can be seen here: http://www.getty.edu/art/exhibitions/making/