 The Codex Sinaiticus, or Book of the Sinai, was written in Greek at the monastery of St. Catherine in the shadow of Mount Sinai. The text contains all of the scriptures of the Old and New Testaments which are accepted by most Christians today. Scriptures that were considered heretical, like the Gospel of Thomas, were left out. The Codex Vaticanus, or the Book of the Vatican, was written in Greek as well, but no one is sure exactly where.