3. vidyāśarīrasattā mantrarahasyam //

The secret essence of mantra
is establishment in the body of
the knowledge of oneness.

———

Here, knowledge means the supreme knowledge of oneness. It is, in the real sense, the supreme God who is the formation of the collection of all sounds. It is from this point that all sounds are created and stored. So, in another sense, it is the state of God consciousness that is one with the universe and filled with supreme I-consciousness.

This is the essence of all mantras. By the words “essence of all mantras” is not meant the mantras such as oṁ namaḥ śivāya, oṁ namo bhagavate vāsudevāya, etc. These mantras are not mantras in the real sense. Mantra, in the real sense, is that supreme I-consciousness. This is the secret about mantras.
This is also quoted in Śrī Tantrasadbhāva Tantra.

All letters are actually one with mantra and those mantras are one with Mother, the energy of Lord Śiva, and that Mother is one with Lord Śiva himself.

Even though this explanation is secret and can’t be exposed or explained, it is revealed in the Tantrasadbhāva Śāstra in this way. This is said by Lord Śiva to Pārvatī:

O Pārvati! There are those who are not maintaining the discipline as taught in the scriptures who do not believe that our master is one with Lord Śiva. They are crooked, attached to worldy pleasures and are not doing any spiritual practice. Because of these misdeeds I have extracted the splendor from their mantras. When that splendor is removed, these mantras become useless. For him who would wield these mantras, they are as good as letters. They have no value. You must have faith that the master is one with Lord Śiva. You must maintain discipline and character. You must not be given to attachment or worldly pleasures. When you live in this way, then your mantra will be filled with splendor and will remain successful.

Now the Tantrasadbhāva explains further:

 That Divine Mother, who is filled with supreme light, has pervaded the whole universe up to brahmaloka. O Devi! Just as all letters are found in the first letter, the letter “a,” in the same way, the whole universe is found in that Divine Mother.

Now I will explain to you some very essential characteristics of this Divine Mother. She is supreme, subtle, not limited to any particular school of philosophy or religion.6 This Divine Mother, called Kuṇḍalinī,7 is placed in the center of the heart.8 There you will find that Divine Mother, just like a serpent in the sleeping state. O Pārvati! There she rests in deep sleep, not perceiving anything other than her own self in a place called mūlādhāra9 by our masters.

In addition, this goddess, places in her body the moon (chandra), fire (agni), the sun (ravi), all the stars (nakṣatra) and all the fourteen worlds (bhuvanāni caturdaśa) and still she is absolutely unaware that this is happening in her own nature.

But how to awaken her? He now explains how this is done.

This goddess cannot be awakened with force. She can only be awakened by (nāda) supreme I-consciousness filled with supreme awareness. To awaken her, the yogī has to churn his point of one-pointedness in the heart, without break, again and again.

He must churn it by inserting sparks of awareness, one after another, again and again, in unbroken continuation. The process is to insert one spark of awareness. Let that one spark fade. Again, insert fresh awareness. Let that spark fade. Again, insert fresh awareness. This process must be continued over and over again in continuity.

Then, the body of energy, which is established in the body of the Divine Mother, kuṇḍalinī, is churned by this awareness. Because of this churning, this yogī will initially experience very intense lights seeming to come from all sides. Because of these lights and that (nāda) supreme I-consciousness filled with supreme awareness, this kuṇḍalinī rises. In the body of that kuṇḍalinī, the yogī finds bindu.10 This bindu, which is residing in the body of the Divine Mother kuṇḍalinī, has four projections radiating from its center.

1. The first projection is that of subjective awareness.
2. The second projection is cognitive awareness.
3. The third projection is objective awareness.
4. And the fourth projection is digestive awareness.

Subjective awareness is awareness of the state of knower (pramātṛi). Awareness of the state of knowledge is cognitive awareness (pramāna). Awareness of the state of the known is objective awareness (prameya). These three kinds of awareness rise from that center of that Divine Mother kuṇḍalinī.

The fourth projection is known as digestive awareness. This is that projection where subjective, cognitive and objective projections are digested in such a way that they are not differentiated one from the other. In the projection of digestive awareness, all these projections are one without distinction. In Sanskrit, this digestive projection is called pramiti bhāva, the digestive state of thought.

O Devi, now you have to simultaneously put the churner and that which is to be churned in that body of kuṇḍalinī. By doing that, kuṇḍalinī, the Divine Mother, rises in a straight line. Here she is called Jyeṣṭhā śakti because she is absolutely established between these two points, the point of subjectivity (pramātṛi) and the point of objectivity (prameya). Then, when these two points (bindu) of subjective awareness and cognitive awareness are also agitated by the process of continual churning, that kuṇḍalinī gives rise to real pure supreme semen and that semen rises from bottom to top in the form of kuṇḍalinī. That kuṇḍalinī is known as the Divine Mother Rekhinī. Here you won’t find either the subjective or the objective projection because these are both diluted in the oneness of that supreme bliss resulting from the rise of supreme semen. At this point, when this semen rises, this yogī immediately comes out from his internal state because he cannot tolerate the joy he is experiencing, which is the creation of that nectar.11 There the Divine Mother is called tripathā because she takes the formation of the three centers. And then again the three centers, the subjective center, the objective center and the cognitive center, rise. And when all these three centers again rise from kuṇḍalinī, the energy of kuṇḍalinī is called Raudrī śakti because it is that energy that puts obstacles in the way in the journey of final liberation.

The yogī must return inside again and again. He must not think that he has lost anything. He need not wait for the master’s direction. Because the way of liberation (mokṣa) is stopped, he must continue to return inside again and again and maintain awareness of that oneness.

Then again she (Ambikā) takes the form of the half moon, which is half inside and half outside.12 And so, even if that supreme Divine Mother is only one, yet she takes these three formations, one for the inferior yogī, one for the yogī who wants to experience enjoyment and one for the superior yogī.

By virtue of these energies of the Divine Mother kuṇḍalinī, nine classes of letters have risen.

1. The first is the class of letters from a to visarga (avarga).
2. The next is the class of letters associated with ka (kavarga).
3. The third is the class of letters associated with ca (cavarga).
4. The fourth is the class of letters associated with ṭa (ṭavarga).
5. The fifth is the class of letters associated with ta (tavarga).
6. The sixth is the class of letters associated with pa (pavarga).
7. The seventh is the class of letters associated with ya (yavarga).
8. The eighth is the class of letters associated with śa (śavarga).
9. And the ninth is the class associated with kṣa (kṣavarga).

All these classes of letters have risen from that Divine Mother Kuṇḍalinī.

There are five sacred states of the self that rise from this kuṇḍalinī and they are the five mouths of Lord Śiva: Iśāna, Tatpuruṣa, Aghora, Vāmadeva and Sadyojāta.13 These mouths have appeared from this kuṇḍalinī so Lord Śiva can speak to the public, helping them and, by illuminating that which is to be known, teach them.14 

Twelve vowels also rise from this Divine Mother kuṇḍalinī, and fifty letters also rise from the same Mother.

And now consider the three kinds of speech: supreme, medium and inferior. The supreme speech is said to be centered in the heart. This supreme speech is the supreme sound, called paśyantī. The throat is the center of madhyamā speech and the tongue is the centre of vaikharī speech.

When something is to be said, it is first to be taken from one’s heart. In the heart, there is no differentiation of letters or words; there is only consciousness. There is some force of what is to occur in the next moment. So in heart, it is just one point, one atom (ekāṇava), and that is called paśyantī speech (vāk).

The next speech (vāk) is called madhyamā vāk. It is centered in the throat.

And the third vāk is called vaikharī, and it is centered in the tongue. It exists when you speak words.

All these sounds appear in the tongue. So, this whole universe resides on sound. This is the process of sound and that sound is carried from that soundless center of kuṇḍalinī.

So, the supreme energy of supreme speech is the source of all speech. This is why all these letters emerge from the supreme center of that energy of God consciousness, the Divine Mother. And all mantras that are recited by spiritual aspirants (sādhakas) get their strength (vīrya) and splendor from that supreme devī of God consciousness, kuṇḍalinī. This is why it is said that Mātṛikā and Mālinī15 both rise from this kuṇḍalinī.

Because the Śiva Sūtras are actually the most secret and essential thoughts of Lord Śiva, in explaining them we have referred to so many tantras. You should not be worried about our giving so many references. And if you still do not understand what kuṇḍalinī actually is, even though we have given so many references to aid your understanding, then you should take hold of the feet of your master.
This meaning of the sūtra is narrated in Spanda in this verse,

All mantras get their life from the Divine Mother kuṇḍalinī. She is the center of all mantras. (Spanda Kārikā 2.1)

Although the strength (vīrya) of the mantra is brought into existence by meditating on the supreme heart of I-consciousness, now and then, by the opposite will of Lord Śiva, the will of concealing (tirodhāna) his nature, some unfortunate men do not realize this I-consciousness and, on the contrary, satisfy their minds with limited yogīc powers.16 This next sūtra explains what will happen to these unfortunate yogīs.

_________________
6. She is not limited to any particular philosophy or religion because anyone—even a cat—can rise if Lord Śiva puts some force in that being.
7. She is called Kuṇḍalinī because she is internal power existing like a serpent in the shape of a coil. Actually, kuṇḍalinī śakti is the revealing and concealing energy of Lord Śiva. This kuṇḍalinī śakti is not different from the existence of Lord Śiva, just as the energy of light and the energy of the heat of a fire are not separate from the fire itself. Kuṇḍalinī, therefore, is, in the true sense, the existence of Śiva. It is the life and glory of Śiva. It is Śiva itself.
8. This heart is not the physical heart. This heart is the center of awareness. It is found everywhere in the body.
9. Mūlādhāra cakra is found near the rectum.
10. Here, bindu refers to the supreme semen (vīrya) that becomes agitated there. The formation of kuṇḍalinī is of that supreme semen. It is not individual semen. It is something beyond that, experienced only by yogīs. Because kuṇḍalinī is formed with the body of supreme semen, which is bindu, just imagine how joyous her formation would be!
11. This is a natural occurrence. He reaches this state of super intense joy and then he comes out from it. This is the way it happens to everyone who experiences this state.
12. This state is the real state of krama mudrā, which is ultimately experienced by blessed yogīs.
13. In the beginning of satyuga, Lord Śiva appeared in the form of Svacchandanātha. As Svacchandanātha, he had five heads and eighteen arms. His five heads came into manifestation through his five great energies: cit śakti (all consciousness), ānanda śakti (all bliss), icchā śakti (all will), jñāna śakti (all knowledge), and kriyā śakti (all action). These five energies appeared in his five mouths known as Iśāna, Tatpuruṣa, Aghora, Vāmadeva and Sadyojāta.
14. Because these five mouths rise from kuṇḍalinī, Lord Śiva is dependent on kuṇḍalinī.
15. Mātṛikā is the system of letters of the Sanskrit alphabet that begins with the first letter a and ends with the last letter kṣa. In the English alphabet this would correspond to the letters a to z. In Kashmir Śaivism, there is another understanding of the system of letters. In this system, the letters are not in order; it is an orderless world of letters. Such a system is one thing in all things and all things in one thing. In Kashmir Śaivism this system is called Mālinī.
16. For instance, flying in the sky, giving boons to disciples, etc.