manuscript book, especially of Scripture, early literature, or ancient mythological or historical annals.
The earliest type of manuscript in the form of a modern book (i.e., a collection of written pages stitched together along one side), the codex replaced the earlier rolls of papyrus and wax tablets. The codex had several advantages over the roll, or scroll. It could be opened at once to any point in the text, it enabled one to write on both sides of the leaf, and it could contain long texts. The difference can be illustrated with copies of the Bible. While the Gospel According to Matthew nearly reached the practical limit of a roll, a common codex included the four Gospels and the Book of Acts bound together, and complete Bibles were not uncommon."
"codex." Encyclopaedia Britannica. Encyclopaedia Britannica Online Academic Edition. Encyclopædia Britannica Inc., 2015. Web. 03 Mar. 2015. <http://academic.eb.com.turing.library.northwestern.edu/EBchecked/topic/123916/codex>.