When, in the first century AD, Pliny wrote about papyrus in his Natural History, it already had been the most common writing material in the ancient world for three millennia (indeed, the word “paper,” itself, derives from the Latin, papyrus).
Papyrus was expensive, and for casual correspondence, such as drafts or notes, student lessons, and even legal and official documents, the wooden writing tablet or tabula cevata, filled with coloured wax, was used instead.


Wood and wax writing tablet 


Although the papyrus roll continued to be used, it was not ideal.


Throughout antiquity, vellum, or parchment as it was later known, had been used as an alternative to papyrus (parchment usually refers to the treated skins of cattle, sheep, and goats; and vellum to that of younger animals).




Eventually, in an important innovation, the Romans substituted parchment for the wooden leaves of the tabula to form the notebook (membranae), which was the prototype of the modern book. Parchment was folded in half to yield a gathering (or quire) of two leaves or four pages, one-half the width of the original (folio). Folding the sheet again gave four leaves or eight pages (quarto); and yet again, eight leaves or sixteen pages (octavo), which was the size of most notebooks.



Wooden tablet writing
Because of its resemblance to a block of wood, the tablet came to be called a codex. There is a similar association in the Latin word for book (liber), which originally meant “bark.” So, too, the Greek name for the papyrus plant, biblos, came to mean the roll made from it, then “book,” and ultimately, the Bible.




That impetus for change from papyrus came from the early Christian church, which adopted the form of the codex to differentiate its writings from the sacred books of Jewish scripture (which could be copied only in the format of the roll) and from pagan literature, which also was equated with the roll.


The codex permitted longer texts, such as the Gospels, to be contained within a single volume and to be referred to more easily. By the second century AD, a shift from papyrus roll to parchment codex was evident. By the fourth century AD, Christianity had triumphed, and the codex replaced the roll, just as, in time, parchment replaced papyrus.


It was a development in the history of the book as monumental as the invention of printing a thousand years later.