Sanskrit Grammar: Vowel Sandhi Rules

Yesterday, I wrote about how to use the Māheśvara Sūtras to uncover the secret rules of Sanskrit written by ancient Sanskrit grammarian Pāṇini. Please review the Māheśvara Sūtras post before proceeding.

In this post, I’d like to go over the different official rules that make up this entire Vowel Sandi chart to understand how it is derived. A big thank you to Dr. Bhaswati Bhattacharya for patiently guiding me through understanding such deep sacred knowledge 🙏

The Sandhi Chart

A Sandhi is when two words are combined into one word. In ancient texts, where each shloka is written in a certain meter called chandas (think Shakespeare iambic pentameter as an example of this), words are combined to compress the number of syllables in a sentence (think “do not” => “don’t”) and also to group certain concepts together.

The Sandhi chart is below:

To read it, take two words and try to combine them. Let’s take आत्मनि (in himself) + एव​ (only) from Bhagavad Gita Ch 3.17. The final letter of आत्मनि is इ. The initial letter of एव​ is ए. Looking at the chart above you will see that the intersecting Sandhi of इ & ए is ये. So the combination of these words becomes आत्मन्येव​.

आत्मनि + एव​ = आत्मन्येव.

How is this chart derived from the Pāṇini shlokas? Let’s start with a shloka I mentioned in the previous blog post as a review and go from there to more rules!

इको यणचि

Pāṇini calls this rule इको यणचि - you can see it in Book 6, Chapter 1, Sutra 77 (6.1.77):

If we undo the Sandhi (letter combinations) of this rule into Padas इको यणचि, the three words that emerge will be इकः यण् अचि.

इकः

इकः refers to all the letters in the Maheshawara Sutras from इ to क्:

१. अ इ उ ण्।
२. ऋ ऌ क्।

So this includes इ ई उ ऊ ऋ ॠ ऌ ॡ.

यण्

The second word यण् refers to all the letters in the Maheshawara Sutras from य to ण् :

५. ह य व र ट्।
६. ल ण्।

So this includes य व र ल.

अचि

अच् refers to all the vowels:

१. अ इ उ ण्।
२. ऋ ऌ क्।
३. ए ओ ङ्।
४. ऐ औ च्।

अ आ इ ई उ ऊ ऋ ॠ ऌ ॡ ए ओ ऐ औ

Putting it Together

This means that when a word with the final letter as इ ई उ ऊ ऋ ॠ ऌ ॡ (इकः) combines with a word that starts with a vowel (अचि), the substitute sandhi letters य व र ल (यण्) should respectively be used as follows:

• इ + vowel = य, ई + vowel = य

• उ + vowel = व, ऊ + vowel = व

• ऋ + vowel = र, ॠ + vowel = र

• ऌ + vowel = ल, ॡ + vowel = ल

Here it is in the light squares on the Sandhi chart I created where a word that ends with a vowel (final) is combined with a word that begins with a vowel (initial):

Note that ॠ and ऌ are not included in this chart, as they are very very rarely used!

Examples:

• कर्मसु (in fruitful activities) + अनुषज्जते (one necessarily engages) = कर्मस्वनुषज्जते (उ + अ = व), Bhagavad Gita, Chapter 6.4

• इति​ (thus) + उच्यते (is said) = इत्युच्यते (इ + उ = यु), Bhagavad Gita, Ch 6.8

• अनुगृह्णाति (maintains) + अविकृतः (normal state) = अनुगृह्णात्यविकृतः (इ + अ = य​), Ashtangra Hrdaya, Sutrasthana, Ch 11.2

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अकः सवर्णे दीर्घः

You might have noticed in the above rule that there were exceptions in the इकः rows that did not follow इको यणचि. That is because when the letters combine together with their twin, the अकः सवर्णे दीर्घः rule is used, reference 6.1.101:

अकः

अकः applies to the Maheshwara Sutras:

१. अ इ उ ण्।
२. ऋ ऌ क्।

This includes the letters अ आ इ ई उ ऊ ऋ ॠ ऌ ॡ.

सवर्णे

सवर्ण means “of the same color”. This refers to when the final and initial vowels of the words that are to be combined are the same. The example given is श्री + ईश​, where श्री ends with an ई and ईश begins with an ई.

However, given that this rule applies to letters “of the same color” as so elegantly stated, combining short and long vowels counts as well. For example, let’s take न (never) + आदत्ते (accepts) from Bhagavad Gita 5.15. न ends in a short अ while आदत्ते starts with a long आ. अ and आ here are of “similar color” 😍

दीर्घः

दीर्घ refers to long vowels -आ ई ऊ ॠ ॡ.

Putting it Together

This rule says that for अकः letters (अ आ इ ई उ ऊ ऋ ॠ ऌ ॡ) - when you combine a word that ends in one of these letters with another one that starts with a letter “of a similar color” - it’s a short or long form, the resulting Sandhi is the long form (दीर्घ) of the letter:

Examples:

• श्री + ईश​ = श्रीश

• न + आदत्ते = नादत्ते

• विष्णु + उदय​ = विष्णूदय​

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एचोऽयवायावः

The next rule is एचोऽयवायावः - according to Pāṇini 6.1.78:

The padas split individual words or padas of एचोऽयवायावः are एचः अय् अव् आय् आव्.

एचः

From the Maheshwara sutras:

३. ए ओ ङ्।
४. ऐ औ च्।

This rule applies to the letters ए ओ ऐ औ.

अय् अव् आय् आव्

The letters ए ओ ऐ औ are substituted with अय् अव् आय् आव् respectively:

ए => अय्

ओ => अव्

ऐ => आय्

औ => आव्

It looks as follows in the Sandhi chart:

Examples:

• चै + अक् = चायकः

• लो + अन् = लवनं

• लौ + अक् = लावकः

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एङः पदान्तादति

You might have noticied that the previous rule did not apply in the case of ए + अ and ओ + अ. This is where the एङः पदान्तादति rule comes in from Pāṇini 6.1.109:

The padas for एङः पदान्तादति are एङ् पदान्तात् अति.

एङ्

From the Maheshwara Sutras, this rule applies to:

३. ए ओ ङ्।

Only ए and ओ.

पदान्तात्

पदान्तात् means final sound.

अति

This refers to the short अ.

Putting it Together

When the final sound of a word is ए or ओ and the initial letter of the next word is अ, then the अ becomes ऽ, an avagraha (or apostrophe) in Sanskrit as follows:

Examples:

• मोक्ष्यसे (you will be released) + अशुभत् (from the miserable material existance) = मोक्ष्यसेऽशुभत्, Bhagavad Gita 9.1

• ते (they) + अन्तमध्यादिगाः (beginning, middle, end) = तेऽन्तमध्यादिगाः, Ashtanga Hrdaya, Sutrasthana Ch 1.7

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आद्गुणः

This rule is a bit confusing and needs some background. It comes from Pāṇini 6.1.87:

The padas for आद्गुणः are आत् गुणः.

आत्

In this case आत् refers to a word that has the final letters as अ or आ.

गुणः

This is the tricky part. To understand what a गुणः is, we have to refer to rule अदेङ् गुणः from Pāṇini 1.1.2:

This says that गुणः includes the letters अ ए ओ. Further, in Pāṇini 1.1.3 इको गुणवृद्धी rule commentary (sorry, I looked at the mentioned sutra but couldn’t find the same mapping like it has it here), it states that the mapping for गुणः is as follows:

The guna of:

• इ or ई = ए

• उ or ऊ = ओ

• ऋ or ॠ = अर्

• ऌ or ॡ = अल्

Keep these mappings in mind!

Putting it Together

So the आद्गुणः rule is saying that when a word ends with an अ or आ, the sandhi substitution should be a guna using the following mapping:

इ or ई = ए
उ or ऊ = ओ
ऋ or ॠ = अर्
ऌ or ॡ = अल्

You can see this in the Sandhi chart:

Examples:

• माला + इन्द्रः = मालेन्द्रः

• तव + ईहते = तवेहते

• खद्वा + उदकम् = खद्वोदकम्

• तव + ऋश्यः = तवर्श्यः

• तव + ऌकारः = तवल्कारः

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वृद्धिरेचि

You might have noticed that the above rule did not apply to all the vowels following अ or आ. That is because the letters initial letters of the next word ए ऐ ओ औ follow an exception rule called वृद्धिरेचि from Pāṇini 6.1.88:

The padas for वृद्धिरेचि are वृद्धिः एचि.

वृद्धिः

However, instead of being replaced by the गुणः letters stated in the previous sutra, these are replaced by वृद्धिः letters mentioned in Pāṇini 1.1.1:

This says that the वृद्धिः letters are आ ऐ औ.

एचि

The एचि rule applies to the following Maheshwara sutras:

३. ए ओ ङ्।
४. ऐ औ च्।

And therefore applies to letters ए ओ ऐ औ.

Putting it Together

So this sutra says that when the final letter of a preceding word is अ आ and the initial letter of the following word is ए ओ ऐ or औ (एचि), then the replacement sandhi should be ऐ or औ (वृद्धिः), which is what we see in the Sandhi table:

Examples:

• ब्रह्म + एडका = ब्रह्मैडका

• ब्रह्म + ओदनः = ब्रह्मौदनः

• ब्रह्म + औपगवः = ब्रह्मौपगवः

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Conclusion

This is probably one of the most fascinating systems of grammar I have ever experienced. It’s like a big complicated puzzle with special keys to figure out at different levels. I LOVE Sanskrit for this!

Note that this is me learning it all and trying to explain it, so I’m sure I’m missing some rules (after all, there are 3,959 of them!) and might not have explained some concepts well. Hope this helps regardless!