information:filtering
Replacement by the codex

The codex form of the book—that is, folding a scroll into pages, which made reading and handling the document much easier—appears during the Roman period. Stemming from a passage in Suetonius' Divus Julius (56.6), legend has it that Julius Caesar was the first to fold scrolls, concertina-fashion, for dispatches to his forces campaigning in Gaul. But the precise meaning of the passage is by no means clear. As C. H. Roberts and T. C. Skeat point out, the idea that " Julius Caesar may have been the inventor of the codex... is indeed a fascinating proposition; but in view of the uncertainties surrounding the passage, it is doubtful whether any such conclusion can be drawn". What the evidence of surviving early codices does make clear is that Christians were among the earliest to make widespread use of the codex. Several Christian papyrus codices known to us date from the second century, including at least one generally accepted as being no later than A.D. 150. "All in all, it is impossible to believe that the Christian adoption of the codex can have taken place any later than circa A.D. 100 (it may, of course, have been earlier)". There were certainly practical reasons for the change. Scrolls were awkward to read if a reader wished to consult material at opposite ends of the document. Further, scrolls were written only on one side, while both sides of the codex page were used.

Eventually, the folds were cut into sheets, or "leaves", and bound together along one edge. The bound pages were protected by stiff covers, usually of wood enclosed with leather. Codex is Latin for a "block of wood": the Latin liber, the root of "library", and the German Buch, the source of "book", both refer to wood. The codex was not only easier to handle than the scroll, but it also fit conveniently on library shelves. The spine generally held the book's title, facing out, affording easier organization of the collection. The surface on which the ink was applied was kept flat, not subjected to weakening by the repeated bending and unbending that scrolls undergo as they are alternately rolled up for storage and unrolled for reading, which creates physical stresses in both the papyrus and the ink of scrolls.

The term codex technically refers only to manuscript books — those that, at one time, were handwritten. More specifically, a codex is the term used primarily for a bound manuscript from Roman times up through the Middle Ages.

From the fourth century on, the codex became the standard format for books, and scrolls were no longer generally used. After the contents of a parchment scroll were copied in codex format, the scroll was seldom preserved. The majority that did survive were found by archaeologists in burial pits and in the buried trash of forgotten communities.