From: Bryan Levman
Message: 4941
Date: 2017-08-25
Dear Dmytro,
dhā, dahati is irregular becaue it comes from Vedic dhā dadhāti (3rd conjugation). One would have expected the same form in Pāli, but the aspirated stop -dh- changes to -h- or aspiirate only. The change of aspirated stops in Old Indic (Vedic) to aspirates only is a common feature of the koine form which is the precursor of Pāli. It was no doubt in part caused by the fact that some of the indigenous languages of India do not have aspirated stops in their phonemic inventory (e.g. proto-Dravidian, proto-Munda and proto-Tibetan). Other Middle Indic Prarkits like Ardha-Magadhi and Gāndhāri also replaced the aspirated stop with an aspirate only, for it is also a normal feature of the synchronic evolution of language over time.
As you noted this change results in a homonym, with the form dahati (“to hold”) being the same as the regular form dahati (‘to burn” < Vedic dah, dahati).
The Vedic root mṛ (“to die”) has two forms, marati (an active form), and mriyati (a passive form). Although there is an active and passive form, they both have the same meaning ("he/she/it dies"). In Pali marati is the same as Vedic, but mriyati > miyyati; ordinarily, in the change of Old Indic to Middle Indic, one would have expected mriyati > miyati with the change of the conjunct mr- > m-. However since in the passive the -i- can be either long (-ī-) or short (-i-), (Geiger §176.2), what appears to have happened here is that the long -ī- was used in the mīyati form, and to compensate for the short -i- in miyati, the -y- was doubled which automatically makes the short -i- long (see Geiger §5)
As you note, this creates a homonym with the root mid whose passive in Vedic is midyate and which naturally becomes miyyate > miyyati (as Pali lost the ātmanepada endings in the pasive, with the normal change of the conjunct -dy- > -yy-.
So yes the stems of daha- (fron the root dhā) and miyya- (or mīya- for the root mṛ) are special in this sense, that they are not a normal evolution. Hope that helps,
Best wishes,
Bryan
1st conjugation √dhā --> daha (irregular) [√dhā - holding; bearing]
1st conjugation √mar --> miyya (irregular) [√mara - abandonment of life; dying]
1st conjugation √daha + a --> daha (regular) [√daha - burning and holding; bearing]
3rd conjugation √mida + ya --> midya --> miyya (regular) [√mida - sticking]
§367. There is a division of the tenses, more fictitious than real, into "Special Tenses" and"General Tenses". From such a division, one would be inclined to think that the former are formed on a special base or modified form of the root, and the latter, therefore, from the root itself. But such in fact is not the case, for it will later on be, remarked that the special and the general tenses not seldom interchange their bases.