Uku and Its Cyrillic Counterpart

Cyrillic uk writes the same vowel and carries the same numeral, four hundred, and here the shared figure is genuinely instructive rather than coincidental. Cyrillic takes four hundred from Greek upsilon, the second letter of the Greek pair that wrote the u sound, and Glagolitic arrives at the same number by counting to twenty two. That the two agree at all through this stretch of the order is what makes numerals in mixed or copied manuscripts so easy to misread: the systems look interchangeable in the middle of the alphabet and are not.

The Cyrillic letter began as two letters written together and was reduced over time to a single sign, and the stages of that reduction are visible across the manuscript tradition. It is one of the clearest cases of a Slavonic letterform having a documented history rather than an assumed one, because the compound and the fused form both survive.

The Glagolitic side has no comparable record, which is the general condition of the script: fewer manuscripts, none of them close in date to the alphabet's making, and a tradition that was displaced in most of its territory before it could leave the trail that Cyrillic left. That imbalance in the evidence shapes every comparison between the two scripts.