Yati Ⱑ

Yati writes the vowel called yat, and it carries no numeral value. Of all the letters in the Slavonic alphabet this is the one that has generated the most scholarship, because nobody is entirely sure what it sounded like and because its later history divides the Slavic languages neatly.

In Old Church Slavonic it is a front vowel distinct from both e and i, and the manuscripts keep it apart from them with reasonable consistency. What its exact quality was is reconstructed rather than known, and the reconstructions differ, partly because the letter developed in different directions in different places. In one language it fell together with e, in another with i, in another it became a diphthong or a distinct vowel that survived for centuries.

That divergence turned the letter into a classification tool. The line across the Slavic world that separates the regions with one reflex from the regions with another is one of the standard boundaries in Slavic dialectology, and it is drawn from the behaviour of this single letter.

Its name is opaque, like the others at this end of the alphabet, and the atlas records the gap rather than filling it.

The letter carries no numeral in either Slavonic script, standing past the end of the Glagolitic count and outside the Greek series that Cyrillic inherited. It is one of the signs that exists purely because Slavonic needed it, which is why its later history is a history of Slavic languages diverging rather than of an inherited convention being maintained.

Yat is the clearest case in the Slavonic alphabet of a letter outliving the sound it was made for and remaining useful anyway. Once the vowel had merged with something else in a given language, the letter had nothing left to distinguish, and a scribe writing that language had to learn by rote which words took it. Spelling reforms in several Slavic countries eventually abolished it, at different dates and after arguments that were as much about national identity as about orthography.

But because the letter went on being written after it had stopped being heard, it preserved information the spoken language had lost. A word spelled with yat in a medieval manuscript can be traced back to a distinct vowel in the parent language even in a region where that vowel had disappeared centuries before, and comparing the same word across languages that resolved the vowel differently is how the original sound is approached at all.

That is the general lesson the letter carries. An alphabet designed for one moment of a language becomes, once the language moves on, a record of the moment it was designed for. The Slavonic scripts were fixed in the ninth century for a South Slavic dialect, and every later Slavic orthography that descends from them carries something of that dialect in its spelling.