Tau, Theta and the Coptic Aspirates

Coptic has a small system of what look like single letters but are better described as compressions. Theta stands for the sequence tau plus hori, phi for pi plus hori, khi for kappa plus hori, and in each case Coptic could write the compressed letter or spell out the two letters instead. Tau is one half of the first of those pairs, which puts it at the centre of a question about the language that grammarians have argued over. The straightforward reading is that these are consonant plus h sequences, written compactly with a borrowed Greek letter because a convenient one was available.

A different reading treats them as genuine aspirated consonants in their own right, phonemes of Coptic rather than sequences, on the grounds that the distribution is not free and that the compressed spellings pattern in ways a mere abbreviation would not. The evidence is spelling, since no one has heard Sahidic spoken for a thousand years, and Bohairic as read in church today has been through its own changes. The practical consequence is straightforward regardless: an editor of a Coptic text records which spelling a manuscript uses, because the preference runs along dialect and workshop lines and is a real piece of evidence about where and when a book was made.