Avestan Dhe: The Letter in the Avestan Alphabet

The sound is a voiced dental fricative, which English spells th in this. English writes the voiced and voiceless members of that pair with the same two letters and leaves a reader to work out which is meant; Avestan gives each its own sign. The dental letters follow the palatals. Five signs are given to this region, the two stops, the two fricatives that answer to them and a further sign restricted to certain positions, which is a larger provision than any neighbouring script of the period made for the same part of the mouth. It stands twenty-ninth in the alphabet as a whole and thirteenth of the thirty-eight consonants, between Avestan De and Avestan Tte. 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. One sign to one sound is the rule this alphabet works to, and it is easier to state than to keep. Most scripts break it somewhere, usually where a sound is rare enough that no scribe could be bothered, and the interest of this one lies in how few exceptions it allows itself.