Zeta: The Coptic Letter (Value 7), from Greek Zeta

Zeta is the seventh letter of the Coptic alphabet and carries the numeral value seven. It joins gamma and delta in the group of Greek letters that Coptic adopted without native need, because Egyptian of the Coptic period had no z sound of its own. The letter therefore lives almost entirely in borrowed material: Greek loanwords, Greek names, and the theological and philosophical vocabulary that came into Egyptian Christianity from Greek. Its numeral value made it independently indispensable, since seven is a number Coptic texts need constantly, from the days of the week to the seven sacraments of the Coptic Orthodox Church and the sevenfold divisions that structure a great deal of scriptural and monastic literature.

Zeta is a particularly good index of the Greek weight of a given Coptic text. In a plain gospel translation it is uncommon; in the Coptic codices from Nag Hammadi, whose contents are translations of Greek religious and philosophical works and are dense with technical terms and with names drawn from Greek cosmological speculation, it appears far more often. Counting a letter is a crude measure of a text, but in a script assembled from two sources it is not a meaningless one, and it shows something about a manuscript before a word of it has been read.