Greek alphabet glottal ("heth") was borrowed in two different functions by different dialects of Greek: as a letter for /h/ (Η, heta) by those dialects that had such a sound, and as an additional vowel letter for the long (Η, eta) by those dialects that lacked the consonant. Eventually, a seventh vowel letter for the long (Ω, omega) was introduced. Greek also introduced three new consonant letters for its aspirated plosive sounds and consonant clusters: Φ ("phi") for , Χ ("chi") for and Ψ ("psi") for . In western Greek variants, Χ was instead used for and Ψ for . The origin
Seventh Letter was any letter from them to Plato, he says. Nevertheless, the "Seventh Letter" has recently been argued to be spurious by prominent scholars such as Malcolm Schofield, Myles Burnyeat, George Boas, Terence Irwin, and Julia Annas. According to Annas, the "Seventh Letter" is "such an unconvincing production that its acceptance by many scholars is best seen as indicating the strength of their desire to find, behind the detachment of the dialogues, something, no matter what, to which Plato is straightforwardly committed." The "Seventh Letter" touches upon a variety of themes, not always in an organized fashion. This article follows Bury