The Rule Behind the Rules

Prakrit grammar and phonology
One general mechanism explains most of the cluster substitutions. Once you see it, you can predict Prakrit forms you have never met before.

Table of Contents

    Series

    Post 5 of 5 in A Beginner's Tour of Prakrit Sound Change — drawn from Hemacandra's Siddhahemaśabdānuśāsana, Adhyāya VIII, Pādas 1–2.

    In the previous post we walked through the famous named cluster substitutions — kṣakkha, tyacca, stattha, and the rest. Behind all of them sits a much simpler mechanism that Hemacandra states in just two rules. If you understand these two rules, you can predict what Prakrit will do with a cluster you have never seen before.

    Examples in:

    A note on the trailing “a”. In Devanāgarī every consonant sign carries a built-in a — क is ka, so the cluster त्य is written tya and its Prakrit result च्च is written cca. In a change such as त्य → च्च (tya → cca) or ट → ड (ṭa → ḍa), only the consonants actually change; the a is there just so the letters can be pronounced.

    The upper-and-lower rule

    When Sanskrit has a two-consonant cluster, Prakrit asks a simple question: which of the two consonants is more sonorous? The less-sonorous one is elided, and the more-sonorous one is doubled to fill the space. Hemacandra puts this in two complementary rules.

    Rule one. If the cluster ends in one of क, ग, ट, ड, त, द, पk, g, ṭ, ḍ, t, d, p, or the sibilants श, ष, सś, ṣ, s — that is, a stop or sibilant — the first (upper) consonant drops and the second (lower) doubles.

    SanskritPrakritWhat happened
    भुक्तbhuktaभुत्तbhuttak dropped, t doubled
    दुग्धdugdhaदुद्धduddhag dropped, dh doubled
    उत्पलutpalaउप्पलuppalat dropped, p doubled
    मुग्धmugdhaमुद्धmuddhag dropped, dh doubled
    खड्गkhaḍgaखग्गkhagga dropped, g doubled
    सिक्तsiktaसित्तsittak dropped, t doubled

    Rule two. If the cluster ends in m, n, or y, the opposite happens — the first (upper) consonant survives and doubles, while the second (lower) drops.

    SanskritPrakritWhat happened
    युग्मyugmaजुग्गjuggam dropped, g doubled
    नग्नnagnaनग्गnaggan dropped, g doubled
    लग्नlagnaलग्गlaggan dropped, g doubled
    कुड्यkuḍyaकुड्डkuḍḍay dropped, doubled
    बाह्यbāhyaबाहbāhay dropped

    That is it. Between these two rules, almost every cluster in Sanskrit has a predictable Prakrit outcome. The named substitutions from the last post are just the specific results of these two general rules applied to specific input clusters.

    क्षKṣaक्खkkha is really k + ṣa: the k is elided, the would become s, and then… well, actually, this specific case is a named exception because the sibilant would produce स्सssa by mechanical rule. Hemacandra names kha as the outcome instead. But you can see the family resemblance.

    And the semivowels vanish everywhere

    There is a third small rule that catches semivowels — the sounds l, v, and r. Wherever they appear inside a cluster, either as the upper or the lower member, they are elided.

    SanskritPrakritMeaning
    ऊर्ध्वūrdhvaउद्धuddhaupward
    चन्द्रcandraचन्दcandamoon
    भद्रbhadraभद्दbhaddagood
    समुद्रsamudraसमुद्दsamuddaocean

    This is why Prakrit almost never contains a r or v inside a cluster. If Sanskrit had न्द्रndra, Prakrit will have न्दnda. If Sanskrit had प्रpra, Prakrit will usually just have pa (with the following consonant doubled).

    Sometimes a vowel is inserted

    Not every cluster can be resolved by dropping one consonant. Some Sanskrit clusters resist that treatment, and Prakrit responds by slipping a vowel — usually a, i, or u — between the two consonants. This is called svarabhakti (literally "vowel-fragmentation"), and it is Prakrit's way of pulling the cluster apart from within.

    SanskritPrakritMeaning
    रत्नratnaरयणrayaṇajewel
    श्रीśrīसिरीsirīfortune
    ह्रीhrīहिरीhirīmodesty
    स्नानsnānaसणेहsaṇeha(also with epenthesis)
    श्लाघाślāghāसलाहाsalāhāpraise
    अर्हतिarhatiअरिहइarihaïhe deserves
    क्लिन्नklinnaकिलिन्नkilinnawet
    स्यात्syātसिआsiāmay be

    You can see the effect clearly in रत्नratnaरयणrayaṇa: the cluster त्नtn would violate the general rules, so a small a is inserted (and the t softens the way we saw in earlier posts). The word grows by a syllable but each syllable is now easy to say.

    A final courtesy: doubling has limits

    The rule that a residual consonant doubles has three quiet exceptions:

    • After a long vowel, the consonant does not double. छूढchūḍha stays छूढchūḍha — the ū has already made the syllable heavy.
    • After an anusvāra (nasal), the consonant does not double.
    • The consonants r and h never double. They simply cannot geminate in Prakrit.

    These small brakes on the doubling rule keep Prakrit from producing forms that would be awkward to pronounce.

    A tour concludes

    Across three posts (five if you count the splits) we have looked at what happens to Sanskrit sounds as they cross into Prakrit. The picture is not complicated once you see the shape of it:

    • Vowels simplify, and long ones shorten before clusters.
    • Single consonants between vowels either drop, become h, or soften a step.
    • Consonant clusters either substitute wholesale into standard outcomes, or resolve by elision-plus-doubling, or split apart with an inserted vowel.

    Hemacandra's grammar catalogues all of this in almost seven hundred aphorisms across four pādas, with careful exceptions marked at every turn. What we have covered here is the mainstream — the general rules that account for most Prakrit words you will actually read. The exceptions are worth learning too, but they will make far more sense once the general shape is in your ear.