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 always represented by pe in its regular, not final, form "פ", even when in final word position, which occurs with loanwords (e.g. שׁוֹפּ ""shop""), foreign names (e.g. פִילִיפּ ""Philip"") and some slang (e.g. חָרַפּ ""slept deeply""). The letters of the Hebrew alphabet have played varied roles in Jewish religious literature over the centuries, primarily in mystical texts. Some sources in classical rabbinical literature seem to acknowledge the historical provenance of the currently used Hebrew alphabet and deal with them as a mundane subject (the Jerusalem Talmud, for example, records that "the Israelites took for themselves square calligraphy", and that the