From Scroll to Codex: How the Book Got Its Shape

Romans wrote on rolled papyrus scrolls for centuries. By the 2nd century CE, Christians popularized the codex, folded sheets sewn at the spine: cheaper, both sides writable, random access, and sturdy.

The shift is visible in surviving biblical manuscripts, almost all codices by 300 CE. Parchment replaced papyrus as supplies dried up, vellum of calfskin became the premium surface, and the codex form survived print and screens as our definition of a book..