Latin for a ‘tablet’ and used to denote an ancient manuscript. Ancient writings were on scrolls, but their disadvantage was having to use both hands to unroll them to find and read the particular passage required. An alternative format was developed in the form of a book with pages which could be turned, and this was gradually adopted by Christians as the most convenient arrangement for public reading. These codices also differentiated the Church from the Synagogues. To make such a book, or codex, sheets of papyrus or parchment were put together.

Two of the earliest codices are from the 4th cent. CE: Codex Vaticanus and Codex Sinaiticus. All ancient Christian MSS of the Greek Bible adopt standard abbreviations for the names of God in both OT and NT—a discreet affirmation of the link between the two Testaments and by implication a rejection of Marcion.