द्विर्वचनेऽचि

This sutra has been explained in different ways by the authors of the Kasika and of the Siddhanta Kaumudi. According to the latter, the sutra means:-- 'when an affix beginning with a vowel follows, that is a cause of reduplication, a substitute shall not take the place of a preceding vowel, whilst the reduplication is yet to be made : but the reduplication having been made, the substitution may then take place.' The explanation given by Kasika is more in harmony with the Great Commentary. For all practical purposes, the two explanations lead to the same conclusion. According to Kasika, the vowel-substitute is sthanivat, in the sense, that it is exactly of the same form as the original, and retains this form only for a fixed time viz., so long as the reduplication is being made; but as soon as the reduplication has been made, the substitute takes its proper form. This rule has its scope in the rules relating (a) to the elision of long आ, (b) to the elision of the penultimate, (c) to the elision of the affix णिच्, (d) to the substitution of semi-vowels for vowels, and lastly (e) to the substitution of अय्, अव्, आय् and आव् for ए, ओ ऐ and औ respectively by the rules of sandhi.

(a). Elision of आ. Let us form the 2nd person perfect tense of the root पा 'to drink.' The termination of 2nd person perfect is अतुस्. This is, therefore, a termination beginning with a vowel, and it causes the reduplication of the root. The conditions of the present sutra all exist in this. Thus we have पा + अतुस् = प् + ० + अतुस् 6.4.64. Here the आ is elided by (VI. 4. 64.) which teaches that 'the आ of the root is elided before ardhadhatuka affixes beginning with a vowel and which are कित् or ङित् and before इट्.' The affix अतुस् is such an affix 1.2.5, 3.4.115.

Now comes the rule about reduplication which is contained in sutra 6.1.8, and teaches that a root consisting of a single vowel is reduplicated before the terminations of the perfect. Here, by the elision of आ, the only visible root left to us is प् which is a consonant without any vowel. The rule of reduplication, therefore, would not have applied to it, because there is no vowel in it, but for the present sutra, which solves the difficulty. Here the vowel-substitute zero must be considered sthanivat i. e. as if it were the very आ itself. Thus we have पा + प् + ० + अतुस् = पपतुस् 7.4.59. The long आ of the reduplicative syllable has been shortened by 7.4.59. So also पपुः ।

(b). The elision of the penultimate. Let us form the same tense of हन् 'to kill.' हन् + अतुस् = ह् + ० + न् + अतुस् 6.4.98.

Here also the preliminary conditions are all fulfilled, the affix begins with a vowel and it causes the reduplication of the root. The penultimate अ of हन् is replaced by the substitute lopa by 6.4.98, which teaches that the roots गम् 'to go' हन् 'to kill' and a few others lose their penultimate before affixes beginning with a vowel and which are also कित् or ङित्. We know अतुस् to be such an affix. For the reasons already given, we can not reduplicate the consonants हन् as they have no vowel. However, this reduplication is effected by virtue of the present rule, and we have:- ह + हृ + अतुस् = जघ्नतुः 7.4.62, 7.3.55. The first ह् is changed into ज् by 7.4.62 and the second ह् into घ् by 7.3.55.

The elision of the affix णिच् . Let us form the Aorist (lun) of the causative form of अट्. The causative is formed by adding the affix णिच् to the root; and the aorist takes the augment अ. Thus we have :- अ + अट् + णिच् + त् = आट् + इ + त्= आट् + इ + चङ् + त्. The affix चङ् 3.1.48 is added in forming the aorist of causatives. The letters च् and ङ् are indicatory, the real affix being अ. Now by 6.4.51, the affix णिच् is elided before an ardhadhatuka affix that does not take the intermediate इ. Now चङ् is such an affix. Therefore we have आट् + ० + अत् .

At this stage, comes into operation another rule 6.1.11, which declares that 'the root is reduplicated before the affix चङ्.' The चङ् is, thus, an affix which causes reduplication; it is an affix which also begins with a vowel. Therefore, it satisfies the conditions of this sutra. Therefore, the zero which was a substitute in place of the vowel इ, becomes sthanivat to इ; as if it were the very इ itself. Thus we have the reduplicative syllable टि, by rule 6.1.2, which says that a verb beginning with a vowel reduplicates its second syllable. But as soon as the reduplication is over, the adesa takes up its original form of zero. Thus आटिट् + ० + अत् = आटिटत्.

(d). The fourth class of cases, where this sutra has scope, is the substitution of यण् for vowels. Thus let us form the perfect and 2nd person singular of कृ 'to do' :- कृ + अतुस् = क्र् + अतुस्, the semi-vowel र् taking the place of ॠ by the general rule of sandhi 6.1.77. Now we have already learned that अतुस् is an affix which causes reduplication and it begins with a vowel. Now र् is a substitute which comes in the place of a vowel (i.e., ॠ), it will therefore be sthanivat by this sutra. Had it not been sthanivat, the consonants क्र् could not be reduplicated, as they have no vowel. The substitute र् being taken equal to ॠ, we reduplicate कृ; in reduplication the क is changed into च् by 7.4.62, and ॠ into अ by 7.4.66. Thus we have:- चक्रतुः; similarly चक्रुः ।

(e). The fifth case is the substitution of अय् &c. Let us form Ist person singular of the perfect of नी 'to lead:' नी + णल् = नै + अ = नाय् + अ. The ई is vriddhied before the termination अ of the perfect 7.2.115, and then changed into आय् by the general rule of sandhi 6.1.78. Now the अ of the perfect causes reduplication, and it is an affix which begins with a vowel. It satisfies the conditions of this sutra. Therefore the आय् which was a substitute for ऐ, being a vowel substitute, becomes sthanivat to ऐ in form. In reduplicating the word नाय्, we reduplicate as if it were still नै. Thus we have the form निनाय and not ननाय. Similarly निनय, लुलव, and लुलाव.

Why have we used the word \dvirvachane\ in the sutra? Without it, the aphorism would have stood thus:-\Before an affix having an initial vowel which causes reduplication, the substitute which takes the place of a vowel is like the original vowel.\ Let us form जग्ले the 3rd per. sing, perfect tense (लिट्) of the root ग्लै \to be exhausted,\ in the atmanepada. The affix of 3rd per. sing. atm. of lit, is एश् 3.4.81. Thus ग्लै + एश् = ग्ला + एश् 6.1.45. Now here ऐ is changed into आ, on account of the affix एश्; this affix causes reduplication, but still आ is not to be considered as sthanivat to ऐ. For if आ be considered so, then in the next stage ग्ला + एश् = ग्ला + ० + एश् 6.4.64 the lopa will be regarded as sthanivat to ऐ and the reduplicative syllable will be जि and not ज; the form being जिग्ले and not जग्ले. But आ is not sthanivat to ऐ, because for the purposes of reduplication, the change of ऐ into आ is immaterial; it is the second and further change of आ into zero which is directly connected with reduplication, (for if zero be not considered sthanivat, there can be no reduplication); and therefore, this substitute zero should be regarded as sthanivat to आ.

Why do we say \which causes reduplication?\ Without these words the sutra would have stood thus:- \Before an affix having an initial vowel, the substitute which takes the place of a vowel is like the original vowel, for the purposes of reduplication.\ In that case we could not get the form दुद्यूषति, 3rd per. sing, desiderative present tense of दिव् 'to shine, to play.' This form is thus evolved :- दिव् + सन् 3.1.7 = दि + ऊ + सन् 6.4.19 = द्य् + ऊ + सन् 6.1.77. Here, the change of इ into य् is caused by ऊ (tech. ऊठ्), which begins with a vowel; is this य् to be regarded as sthanivat to इ? No, because ऊ does not cause reduplication, it is सन् which causes reduplication. Therefore the equation is :- द्यू + सन् = दुद्यूस 6.1.9 = दुद्यूषति. If य् could be regarded like इ, then the form would have been दिद्यूषति.

Why do we say \beginning with a vowel\? Otherwise the sutra would have run thus:- \Before an affix which causes reduplication, the substitute which takes the place of a vowel, is like the original vowel, for the purposes of reduplication.\ The affix यङ् of the Intensive verbs causes reduplication 6.1.9; but as it does not begin with a vowel, the substitute will not be sthanivat. Let us form जेघीयते the 3rd per. sing. Intensive of the root घ्रा 'to smell.' Thus घ्रा + यङ् = घ्री + यङ् 7.4.31 = जेघ्रीयते 7.4.82. Here, आ is changed into ई on account of यङ्; but ई is not sthanivat to आ; had it been so, the form would have been जघ्रीयते. Similarly देध्मीयते.,