Avestan Sshe: The Letter in the Avestan Alphabet

This is the fourth of the alphabet's sh type signs, transliterated with a dot beneath, and the manuscripts keep it apart from the other three. Four separate letters for sounds that most writing systems gather under one is the clearest single measure of how finely this alphabet cuts. The sibilants close the consonant section before the final letter, and they are the largest family in the alphabet: six signs, where the scripts around it managed with two or three. The group runs from the plain s and z through the sh sounds, of which there are four. It stands fifty-third in the alphabet as a whole and thirty-seventh of the thirty-eight consonants, between Avestan Shye and Avestan He. That position is not arbitrary.

The sequence follows a scheme, vowels before consonants and consonants by place of articulation, and each letter's place in it is a statement about the sound. The tradition calls the script din dabireh, the religion writing. It served the Avesta and very little else, and the shape of its letter list follows the sounds of that one language rather than any general requirement of writing in Sasanian Iran. Avestan is written from right to left, a direction inherited along with the letterforms. What was not inherited is the practice of writing every vowel, and that single departure is what makes the script legible to somebody who does not already know the word in front of them.