तुल्य-आस्य-प्रयर्नं सवर्णम्

This defines the word savarna or a homogeneous letter. The sūtra consists of four words :- तुल्य \equal or similar,\ आस्य \mouth or place of pronunciation,\ प्रयत्न \effort\ and सवर्णम् \words of the same class.\

The आस्य or places or portions of the mouth by contact with which various sounds are formed are chiefly the following :- 1. कण्ठ \throat\ 2. तालु 'palate,' 3. मूर्द्धा, 'head,' 4. दन्ताः 'teeth,' 5. ओष्ठौ 'lips,' 6. नासिका 'nose.'

The प्रयत्नम् or quality or effort is of two sorts primarily, आभ्यन्तरः \internal\ and बाह्यः \external.\ The first is again sub-divided into five parts:-

1. स्पृष्टम् or complete contact of the organs. The twenty-five letters from क to म belong to this class. In pronouncing these there is a complete contact of the root of the tongue with the various places, such as throat, palate, dome of the palate, teeth and lip.

2. ईषत्स्पृष्टम् or slight contact. The letters य, र, ल, व belong to this class of contacts. \In pronouncing these semi-vowels the two organs, the active and passive, which are necessary for the production of all consonantal noises, are not allowed to touch each other, but only to approach.\

3. विवृतम् or complete opening. The vowels belong to this class.

4. ईषद् विवृतम् or slight opening. The letters श, ष, स, ह belong to this class. Some however place the vowels and श &c., into one group and call them all vivrita.

5. संवृतम् or contracted. In actual use, the organ in the enunciation of the short अ is contracted but it is considered to be open only, as in the case of the other vowels, when the vowel अ is in the state of taking part in some operation of grammar.

The abhyantara prayatna is the mode of articulation preparatory to the utterance of the sound, the båhya-prayatna is the mode of articulation at the close of the utterance of the sound.

The division of letters according to abhyantra prayatna has been already given. By that we get, 1. the sparsa or mute letters, 2. the antastha or intermediate between sparsas and ushmans, or semi-vowel or liquid letters, 3. the svaras or vowels or vivrita letters, 4. the ushmans or sibilants or flatus letters.

The division of letters according to båhya prayatna gives us first surds or aghosha letters, 2. sonants or ghosha letters. The aghosha are also called svasa letters, the ghoshas are called nåda letters.

The second division of letters according to båhya prayatna is into;

1. Aspirated (mahåprana). 2. Unaspirated (alpaprana).

The vowel अ has eighteen forms. The acute अ (udatta), grave अ (anudatta) and circumflexed अ ( svarita). Each one of these three may be nasalised (anunasika), or not (niranunasika).

Then lastly everyone of these six may be short, long, or prolated. Thus:- अ, अ॒, अ॑, अँ, अँ॒, अँ॑, आ, आ॒, आ॑, आँ, आँ॒, आँ॑, अ३, अ॒३, अ॑३, अँ३, अँ॒३, अँ॑३.

Similarly the letters इ, उ and ऋ have also eighteen forms. The letter ऌ has no long form; it has therefore 12 modifications. The diphthongs have no short forms, they have therefore, only 12 forms. The antastha or semi-vowels with the exception of र have two forms each vis., nasalised and un-nasalised. The semi-vowels have no homogeneous letters corresponding to them. All letters of a varga or 'class' are homogeneous to each other.

Thus then the homogeneous or savarna letters must satisfy two conditions before they could be called savarna. First, their place of pronunciation or आस्य must be the same. Secondly their प्रयत्न or quality must be equal. If one condition be present and the other be absent, there can be no savarna-hood. Thus च and श are both palatals, their आस्य or place of pronunciation being तालु 'palate', but still they are not savarna, because their प्रयत्न is different, the प्रयत्न of च being sprishta and that of श being vivrita.

Similarly क and च though their प्रयत्न is the same i.e., sprishta, yet their आस्य being different, one being guttural and the other palatal, are not savarna.

There is exception to this rule in the case of ऋ and ऌ, which though having different आस्य are still called savarna by virtue of the varttika of Katyayana; \the homogeneousness of ऋ and ऌ , one with another, should be stated.\ Thus होतृ+ऌकारः = होतॄकारः ; here ऋ and ऌ have coalesced into long ॠ by rules of sandhi, on the assumption that they are savarna letters.

The word savarna occurs in sůtras like अकः सवर्णे दीर्घः 6.1.101.

Why do we say \the place of pronunciation\? So that there may not be homogeneous relationship between कचटत and प whose prayatna is the same but whose åsya is different. What is the harm if we make them savarna? Then in words like तर्प्ता and तर्प्तुम्, the प would be elided, if it be held homogeneous with त, by 8.4.65, \there is optional elision of झर्, preceded by a consonant, when a homogeneous झर् follows.\

Why do we say \effort\? That there may be no homogeneity between इ and the palatals, and य and श, whose organ of pronunciation is the same, but whose prayatna is different. What harm if it be so ? Then in अरुश्च्योतति, the श would be elided before च by the rule already referred to, 8.4.65.,