Yeri Ь

Yeri stands thirty first and writes the front jer, the second of the two reduced vowels of Old Church Slavonic. It carries no numeral value.

Like its back counterpart it was a real vowel in the earliest texts, short and weak, written wherever it was spoken. Its second function was to say that the consonant before it was softened, and when the vowel itself fell silent in the sound change described on the entry for yer, that second function was all that remained.

The letter therefore became a diacritic in the shape of a letter. Modern Russian calls it the soft sign, and it is one of the few letters in any alphabet whose entire job is to modify the letter before it while representing no sound of its own. Ukrainian, Belarusian and Bulgarian keep it too, with the same function and slightly different rules.

That transformation is worth stating plainly, because the modern letter is often described as though it had always been a mark of softness. It had not. It was a vowel that happened to imply softness, and it survived because the implication turned out to be more useful than the vowel. The alphabet that came out of the ninth century did not contain a single letter of this kind, and neither did the language it was made for.

The distinction between hard and soft consonants carries an enormous amount of grammatical information in the Slavic languages, and a writing system has to record it somehow. There are only two ways: mark the consonant, or mark the vowel that follows it.

Cyrillic chose the second, and the choice is visible throughout the alphabet. Slavonic wrote a glide plus a vowel with its own letters, the iotified series, and the modern alphabets continue the principle with vowel letters that do double duty, saying both which vowel is present and whether the consonant in front of it is soft. On that system the reader learns the consonant quality by looking one letter ahead.

The system has a gap. A soft consonant at the end of a word, or in front of another consonant, has no following vowel to carry the information, and there the front jer steps in. Modern Russian orthography is exactly this: vowel letters do the work where a vowel follows, and the soft sign does it where none does.

That is a tidy solution to a real problem, and it was not designed. It is the accidental outcome of a vowel falling silent and leaving its side effect behind, and it happened to land on a script whose vowel letters were already carrying consonant information for unrelated reasons.

The alternative approach, marking the consonants themselves with diacritics, is what the Latin based Slavic orthographies do, and comparing a Czech page with a Russian one shows two entirely different answers to one question.