About the Mystery of the Letters the mid-6th century, in which Mar Saba had played an important role. The anonymous author of the treatise declares he was prompted to the study of the secret meanings of the letters by the words of the Apocalypse, "I am the Alpha and Omega", and that he subsequently received a vision about them on Mount Sinai. The author proposes a re-modelled Greek alphabet reduced to 22 letters on the model of the 22 letters of Hebrew (discounting Xi Ξ and Psi Ψ), and with the Hebrew letter names. He then interprets these letters as symbolic figures of 22 works of
Hebrew alphabet from that in the Book of Genesis, largely through exposition on the powers of the letters of the alphabet. The supposed creative powers of the letters are also referenced in the Talmud and Zohar. Another book, the 13th-century Kabbalistic text Sefer HaTemunah, holds that a single letter of unknown pronunciation, held by some to be the four-pronged shin on one side of the teffilin box, is missing from the current alphabet. The world's flaws, the book teaches, are related to the absence of this letter, the eventual revelation of which will repair the universe. Another example of messianic significance attached