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 indicated by the "dagesh". In Modern Hebrew the sounds ḏ and ḡ have reverted to and , respectively, and ṯ has become , so only the remaining three consonants show variation. "resh" may have also been a "doubled" letter, making the list "BeGeD KePoReT". (Sefer Yetzirah, 4:1) The following table contains the pronunciation of the Hebrew letters in reconstructed historical forms and dialects using the . The apostrophe-looking symbol after some letters is not a yud but a geresh. It is used for loanwords with non-native Hebrew sounds. The dot in the middle of some of the letters, called a