The codex was written between 400 and 600 AD, in southern Egypt. “The charred codex was purchased by the Morgan Library in 1962. But no one has opened it for fear of destroying it: The brittle pages have been fused together by a cinder that sank through much of the book, congealing the parchment fibers. Unlike famous codices that have their own names, like the Codex Sinaiticus, this one is known humbly as M.910.”