A Sound the Script Does Not Distinguish

Between vowels in many Middle Indo-Aryan dialects the voiced retroflex stop weakened towards a flap, a sound made by the tongue striking the roof of the mouth in passing rather than closing against it. Brahmi has one letter and writes both, so a reader has to take the value from the language rather than from the sign. That is an ordinary difficulty of the earliest Indic epigraphy, and it is one of several places where the script records less than a modern reader would like.

Vedic recitation makes a related substitution and preserves it in writing. In the received text of the Rigveda an intervocalic occurrence of this stop is read and written as the retroflex lateral instead, the letter that stands last in the Brahmi consonant order, and the substitution is described in the classical grammars. Classical Sanskrit does not make it. So the same underlying sound appears under two different letters depending on which stage and which register of the language is being written, which is a reminder that an alphabet records a tradition of pronunciation and not a set of abstract sounds. Several of the descendant scripts eventually resolved the flap problem by adding a subscript dot to this letter, a distinction Brahmi never had.