A book is an object whose mechanism must "work"; therefore, the bookbinding process should not be haphazard, accidental, or capricious. When the book lies open on a flat surface, its pages must rest on the covers on both sides. This depends on the quality of the paper, good stitching, and a space between the book block and the spine that provides flexibility to the spine, which is the book's true hinge. The stitching of the signatures should allow the book to open effortlessly; a book with loose, glued pages will never open comfortably. On the other hand, if the endpaper is not tightly fitted to the cardboard hinge, it will pull on the first few pages, tearing the signatures and exposing the stitching.

Historically, the physical properties of the book block have determined the type of binding, both in terms of the materials used and its structure. The Western codex, made of parchment leaves and initially intended for liturgical use, was therefore very heavy and large. To prevent spine warping, it required a stronger stitch than the simple chains of thread used in Eastern codices. This led to the incorporation of leather or cord raised bands, which also allowed for the sewing of sturdy wooden covers to the book block, instead of the papyrus padding of the earliest Eastern codices. It was this need to sew over raised bands that led to the spread of the loom in the West between the 8th and 11th centuries. The codex became lighter when its private use justified the proliferation of smaller formats and when paper, lighter and more flexible than parchment, was widely adopted. Being lighter, the book no longer needed thick cords or heavy covers. Renaissance bindings in full embossed leather retained the external raised bands and wooden boards, but flexible parchment bindings and "papier-mâché" covers were also found, and the "alla greca" stitch was used for Greek manuscripts in the great European libraries. This type of stitching, in which the raised bands are very fine and embedded in the body of the book, became widespread from the 18th century onward, with the "natural" raised bands disappearing and being imitated with "false" raised bands of leather, cord, or cardboard, glued under the leather of the spine. Likewise, the headbands, whose purpose is now purely ornamental, had, like the original raised bands, a structural function. On the one hand, they reinforced the stitching by joining the ends of the signatures; On the other hand, it must be taken into account that in the first libraries of codices, these were stored horizontally, and therefore to take the book off the shelf it could be pulled not only by the head, but by both ends; the head prevented - or at least delayed - the tearing of the headband.

This is an excerpt from
a lecture given in the Humanities Library of the
Autonomous University of Madrid on April 23, 2014, entitled Historical Morphology of the Book.