E and the Ladder of Strengthening

The four combination vowels exist in the alphabet largely because of a mechanism that runs through the whole of Sanskrit word formation. The grammarians describe a ladder of strengthening applied to the vowel of a root when derivatives and certain tenses are built from it, with two steps above the basic grade, called guna and vrddhi. Short i strengthens to e at the first step and to ai at the second; short u strengthens to o and then to au. The four sandhyakshara are therefore not decorative additions to the vowel series but the products of a systematic process, and their presence in the table is the table recording that process.

Panini states the strengthening rules in the Ashtadhyayi using the abbreviations built from the Shivasutras, and the economy of that statement is one of the things that has made the grammar an object of study in its own right for well over two thousand years. For a reader of the atlas the practical consequence is that e is common, that it is always heavy, and that its presence in a word often signals a derived form rather than a root.

In the Tantric arrangement of the alphabet the vowels stand as a class before the consonants and this letter is one of the fifty matrika counted in the garland. What individual schools make of it beyond that is theirs, and the scholarly literature presents those readings as the positions of particular traditions rather than as a single system.