Tilak’s observation
I may, however, remark that the process which appears so simple according to the modern philological rules, was not recognized by the native grammarians. There are good many words in Sanskrit which can be thus easily derived on the principle of the insertion and omission of h.+++(5)+++ Thus we have invakā and hinvakā both meaning the stars on the top of Mrigashiras, and aṭṭa and haṭṭa denoting a marketplace. But native grammarians, including Pāṇini, would not derive the words from each other, as we have done above in the case of ayana and hayana. Their method is to give two different roots for the two words, thus we have two Vedic roots hinva and inva or hiv and iv, both meaning to go, to please, the one giving us hinvaka and the other invaka. Aṭ and haṭ, an and han, ay and hay, i and hi are further instances of the principle adopted by the native grammarians in such cases.
Really speaking this is not solving the difficulty, but only shifting it a stage backwards ; for if any explanation is pecessary to account for the double forms like ayana and hayana, it is equally required to explain why we should have the double roots like ay aod hay, both meaning to go. But it appears that the native grammarians having traced the words to their roots, did not push the matter further.+++(4)+++ With them ina is derived from i to go, ayana from ay to go, hayana from hay to go, and hayana from na to go.* (* This method sometimes fails, and native grammarians who are not now at liberty to coin new roots, have to resort to the Pr̥ṣodarādi list. For example, we liave two forms ilvalā and hilvalā as different readings for invakā in Amara i. 3. 23. Of these ilvalā can be derived from it, to sleep, though the root meaning is not suitable, but hālvalā cannot be even so derived and Tārānātha in bis Vācaspatya would derive or rather obtain the initial h by Pr̥ṣodarādi. Similarly cf. hintāla = tāla + Pr̥ṣodarādi!)