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 letters "came with the Israelites from Ashur [Assyria]"); others attribute mystical significance to the letters, connecting them with the process of creation or the redemption. In mystical conceptions, the alphabet is considered eternal, pre-existent to the Earth, and the letters themselves are seen as having holiness and power, sometimes to such an extent that several stories from the Talmud illustrate the idea that they cannot be destroyed. The idea of the letters' creative power finds its greatest vehicle in the Sefer Yezirah, or "Book of Creation", a mystical text of uncertain origin which describes a story of creation highly divergent