Codex Bezae is laid out for a reader working in two languages at once. The Greek stands on the left-hand page and the Latin on the right, one column to a page, and the lines are broken where the sense breaks rather than run out to the margin, so the two versions can be followed against each other line for line. It was made around the year 400, on vellum, by a scribe who understood both texts well enough to keep them in step, and the discipline that took is easy to underestimate: a bilingual page has to be planned before it is written, because a line that runs long on one side has nowhere to go on the other.
Four hundred and six leaves survive of perhaps five hundred and thirty. It contains the four Gospels in the order Matthew, John, Luke, Mark, an order found in some other early western books and not in the later standard, then a fragment of 3 John, then Acts. The losses are substantial and fall throughout, and one leaf that had been given up as gone was recovered in the twenty-first century by imaging the ink that had offset onto the page it once faced.
Where the codex was made is genuinely unsettled. Southern France, north Africa, Egypt, Palestine and Beirut have all been argued, from its script, from the quality of its Latin, from its spellings and from the particular kinds of mistake its scribe makes. No proposal has become consensus. That uncertainty matters more here than it would for another book, because what makes Bezae important is how unlike every other early manuscript it is, and knowing where an unlike thing came from would go a long way towards explaining why.