How some Nātha yogis influenced a number of Tantric schools.

The earliest Nātha yogis were associated with the Kāpālikas, I’ll give you one example. In Buddhism, there is a yogi who is known as Kṛṣṇācārya, and as Kṛṣṇanāth in the Nātha-sampradāya, also Kanipānātha – Kānhapā. He was a disciple of Jalandharnāth, who is famous among both Nāthas and Vajrayāna Buddhists. Both of them are included in the list of the Nine Nāthas in Maharashtra.

Kānhapā practised Kāpālika sādhanās also the Hevajra-tantra. It is believed that the practice of tummo was received from him by Marpa, then by Milarepa and later by Naḍapāda, better known as Naropa, who compiled his famous six yogas based on tummo.

It is believed that in the practice of tummo or caṇḍālī, which is actually kuṇḍalini-yoga, an important element is karma-mudrā, a practice, similar to Vāmācāra maithuna in kaulism. This method allows you to sublimate the sexual fire into the inner fire of kuṇḍalini or caṇḍālī. Other yogas, such as yoga of light, yoga of dreams, etc. develop from this practice of inner yoga. But the main purpose of tummo is to awaken within oneself a state of bliss and emptiness, which ultimately leads to the level of mahā-mudrā, also known as Dzogchen. These highest levels of practice may vary among different teachers and Vajrayāna lineages. In the Nāthas’ texts, namely the Akulavīratantra, the Amanaska Yoga, etc., this state is called sahajānanda. Obviously, at some stage, those ancient yogis borrowed terms from each other, actually, Vajrayāna was called “Sahajayana“, although Vajrayāna indicates an indestructible state realised in the vajra-nāḍī through the basic practice of tummo (kuṇḍalini-jāgaraṇ). Sahaja means “to be together with the innate,” which, according to one interpretation, is the joint fusion of male and female bindus in the sahasrāra-cakra. Actually, this is the practice that in Buddhism is called Dzogchen, which, according to one interpretation, is an analogue of mahābindu. The essence of Dzogchen/Mahāmudrā practices is staying in your natural perfect state, known among the Nāthas as sahajananda.

Later these methods were adopted by the Sahajiya Vaiṣṇavas, their methods were very similar to the methods of tantric yoga of the Nāthas and Vajrayāna, however, with the arrival of the British, many Vaiṣṇavas Sahajiya gurus in Bengal went underground. These practices are already considered secret, but the Puritan British (at that time) further influenced the secrecy of these traditions. Instead, some Indian Westernised gurus, such as Bhaktivinoda Ṭhākur and others, were forced to create “refined” forms of Vaiṣṇavism, which later came to America and other countries.

India changed a lot with the arrival of the British, it became much more difficult to identify authentic yoga, authentic learning in Tantrism, etc. This is all seriously complicated by the fact that most Indian gurus are trying to Westernise. You will find a huge amount of such yoga in touristic places. Often, even in the Traditions themselves, with the ancient lineage, not all gurus want to seriously teach someone, but even less of their Western “disciples” are ready to fully study. Therefore, many of gurus think, “I will earn money at least, then life will show whether appear anyone, who can be taught seriously or not.” Again, someone who has realised himself in sādhanā, can teach with sufficient spiritual purity, but most teachers often try to teach without strong experience in sādhanā.

I have described the situation very briefly without touching on many other details, that I would draw the attention of those who are looking for the basics of authentic tantric yoga. But, even this can help in the search for those, who have sufficiently serious motivation.

The fifth makara in tantra practice

I translated a small part of the Experience in Spiritual Practice (साधना के अनुभव), the book by Rameshchandra Sharma. I think this information will be useful for many practitioners to understand the maithuna topic in Tantrism. It is necessary to practice the maithuna ritual when the sexual energy stagnates in the area of the mūlādhāra and svādhiṣṭhāna cakras. When the kuṇḍalinī ascends, the practice with it becomes a form of yoga, which is mainly contemplative. Of course, these boundaries are very relative, however, there is a general principle of connecting the two poles in order to sublimate our vision and energy. Here is the text:

The Fifth of the Five Makaras

In tantric sādhanā, the practice of pañcamakāra is found. Practice with madya (wine), māmsa (meat), etc., it can also be done with their substitutes. In the pañcamakāra, the fifth is associated with the sense-oriented pūjā, which is known as maithuna. In essence it leads to the regulation of the semen. Maithuna is also called “latasādhanā“, it is a special practice for awakening the svādhiṣṭhānacakra.

Often after the awakening of the kuṇḍalinī, when vāyu (energy) rises to the svādhiṣṭhānacakra, kāma (passion), ascending there, begins to transform into what we know as yogasādhanā. Through the identification of a woman with Devī (Goddess) and himself with Śiva, the practitioner leaves the gross states of the physical body, and his spirit and consciousness are directed to the sphere of spiritual consciousness. This often happens when practicing a mantra with prāṇāyāma. The power in the svādhiṣṭhāna or maṇipūracakra begins to intensify and the practitioner through asceticism becomes an ūrdhvareta – one, whose ascending sexual power is sublimated. Near the maṇipūracakra (just below it) in a woman is the womb (garbhāśaya), which is the most important area in their body. 

So, from the svādhiṣṭhānacakra to the maṇipūracakra there is a point of two poles, the connection of the spiritual and the physical. and through the practice of japa you connect these centers in a pure sāttvic state. In a state of full bloom of power, at the beginning of the practice, you use a special method, thanks to which the power increases and moves further in the direction of the anāhatacakra. Mental worship is the essence, thanks to which everything basic happens there.

In the daily pūjā you can invoke the Goddess into a red flower (yellow in the case of Bagalāmukhī), and invoke Śiva in a white flower. Place the flower where the Goddess is on top of the white flower of Śiva, that will be the symbol of viparīta-rati, symbolically connecting Śiva and Śakti.

Aṣṭa mudrā (the Eight Mudras)

This part is an appendix to the Gorakhbani, a text published by the Gorakshanath Mandir, Gorakhpur. The mudras, especially the five of them in the head area, are described in many Nathā texts, their practices are interpreted there in different ways. The ideal option is when the Guru in a live presentation transfers them to his disciple. For example, khecarī here is associated with taste, someone understands this as control of taste, but others understand taste as Śakti and lack of taste as Śiva, their union is khecarī-mudrā. The same applies to other mudrās, because they all require oral transmission, where the Guru (who is, of course, an experienced practitioner and has achieved high success in the practice of “siddhi“) can convey the essence to a worthy student.

अष्ट मुद्रा स्वामीजी अष्ट मुद्रा बोलिए घट भीतरी, ते कौंण कौंण ।
Tell me, Swamiji, what are the eight mudrās inside the body?

अवधू यंद्री मध्ये मूलनी मुद्रा, काम त्रिष्णा ले उतपनी काम । काम त्रिष्णा समो कृतवा, मुद्रा तो भई मूलनी ।।
O avadhu, in the middle of the perineum is the mulanī-mudrā associated with sex (kāma) and greed (tṛṣṇā). The control of kāma and tṛṣṇā is mūlanī-mudrā.

नाभी मधे जलश्री मुद्रा, काल क्रोध ले उतपनी । काल क्रोध समो कृतवा, मुद्रा तौ भई जलश्री॥
There is jalśrī-mudrā in the umbilical centre, time and anger rise there (Kālabhairava or Kālāgnirudra symbol). The control of time and anger is jalśrī-mudrā.

हुदा मधे षिरनी  मुद्रा, ग्यांन दीप ले उतपनी। ग्यांन दीप समो कृतवा, मुद्रा तो भई पोरनी॥
There is ṣirnī  (or kṣīriṇī) in the centre of the heart, there is the perception of the rising light of wisdom. When one’s knowledge shines there, then this wisdom is realised.

मुष मध्ये षेचरी  मुद्रा, स्वाद विस्वाद ले उतपनी। स्वाद विस्वाद समोकृतवा, मुद्रा तो भई षेचरी ।।
In the centre of the mouth is khecarī-mudrā, the manifestation of taste and its absence is perceived there. If there is harmony there between taste and absence (also between pleasant and unpleasant taste), it is khecarī-mudrā.

नासिका मध्ये भूचरी मुद्रा, गंध विगंध ले उतपनी। गन्ध विगन्ध समो कृतवा, मुद्रा तौ भई भूचरी ।।
In the centre of the nose is bhūcarī-mudrā, there we get odour or lack thereof (also pleasant and unpleasant smells). If there is odour control or lack thereof (also pleasant and unpleasant smells), it is bhūcarī-mudrā.

चषि मध्ये चाचरी मुद्रा, दिष्टि विदिष्टि ले उतपनी । दिष्टि विदिष्ट समो कृतवा, मुद्रा तौ भई चाचरी।।
At the centre of the eye is cācārī-mudrā, the perception of what is visible and invisible rises there. If there is harmony and control of the visible and invisible, that is cācārī-mudrā.

करण मध्ये अगोचरी मुद्रा, सबद कुसवद ले उतपनी। सवद कुसबद समो कृतवा, मुद्रा तौ भई अगोचरी।।
There is agocarī-mudrā in the centre of the ears, pleasant and unpleasant speech is manifested there. If there is evenness with regard to pleasant and unpleasant speech, it is agocarī-mudrā.

ब्रहमंड असथांनि उनमनी मुद्रा, परम जोति लै उतपनी। परम जोति समो कुतचा, मुद्रा तो भई उनमनी ।।
In the universe there is unmanī-mudrā (the symbol of the unfolding mind), the Supreme light is manifested there. If this supreme light (consciousness) is evenly distributed everywhere, then it is unmanī-mudrā.

यती अष्ट मुद्रा का जाणै भेव । सौ आपै  करता भेवे ।। इती अष्ट मुद्रा कर्थत श्री  गोरषनाथ  जती संपूर्ण समापत सिवाय ।
One who knows these various mudrās has a higher nature. Thus ends the complete explanation of the eight mudrās by Gorakṣanāth.

Why do the texts say that paścimottānāsana activates suṣumṇā and awakens the kuṇḍalinī?

It so happened in India, that spiritual practices are most often performed facing east. Accordingly, the west (conditionally) is our back, the south is the right and hot side and the north is left and cold. The Sun is associated with vital power, it rises in the east and sets (i.e. disappears) in the west. We fall asleep at sunset and our senses become silent, and they turn on at sunrise. We can see basically everything that is in front of us, on the sides, below and even sometimes from above, but we cannot see our back. We can only feel it, while there should be an inversion element, i.e. direction inward, listening to our sensations inside. The west is a symbol of the extinction of activities, the completeness of them, so it is suṣumṇā. It is also no coincidence that one of the well-known traditions, where kuṇḍalinī is worshiped in the form of the Goddess Kubjikā, is called paśchimāmnayā – the Western Doctrine. Paśchima – from paścāt (behind, the last, completed, western), therefore it is a symbol of suṣumṇā, self-absorption. Thus, paścimottānāsana is focused specifically on the direction of attention and the prāṇa in suṣumṇā along with it. This āsana is also focused on the conscious activation of suṣumṇā with pratyāhāra and the awakening of the kuṇḍalinī power.

Four aspects of the Laya process

इन्द्रियाणां मनो नाथो मनोनाथस्तु मारुत:।
मारुतस्य लयो नाथ: स लयो नादमाश्रित: ।। ॥ २ ९॥

indriyāṇāṁ mano nātho manonāthastu mārutaḥ |
mārutasya layo nāthaḥ sa layo nādamāśritaḥ || 29 ||

1) The mind (manaḥ) is the lord (nāthaḥ) of the senses (indriyāṇām).
2) Also (tu) vital force (mārutaḥ) is the lord (nāthaḥ) of the mind (manaḥ).
3) Dissolution (layaḥ) is the lord (nāthaḥ) of air (mārutasya).
4) And that (sa) depends (āśritaḥ) on resonance (nādam). (Haṭhayogapradīpikā 4.29)

Gorakśanātha-upāsanā according to the Kalpadruma Tantra

I translated the tantric Gorakśanātha-upāsanā according to the Kalpadruma Tantra at the request of my students.

विनियोगः। viniyogaḥ

ॐ अस्य श्री गोरक्ष मन्त्रस्य बृहदारण्यक ऋषिः अनुष्टुप् छन्दः श्री गोरक्षनाथो देवता गों बीजम् विमला शक्तिः   हंसेति कीलकं निरञ्जनात्मक सर्व तत्त्व सिद्धये जपे विनियोगः ।।

oṃ asya śrī gorakṣa mantrasya bṛhadāraṇyaka ṛṣiḥ anuṣṭup chandaḥ śrī gorakṣanātho devatā goṃ bījam vimalā śaktiḥ haṃseti kīlakaṃ nirañjanātmaka sarva tattva siddhaye jape viniyogaḥ ।।

The ṛṣi of the Śrī gorakṣanāthamantra is Bṛhadāraṇyaka, the rhythm is anuṣṭup, the Divine is Gorakṣanātha, the bija is goṃ, the Śakti is Vimalā (pure), the kīlaka is haṃsa, the ritual of japa for success in the essential purity of all tattvas.

ऋष्यादिन्यासः । ṛṣyādinyāsaḥ (the nyāsa starts from the head and so on)

ॐ बृहदारण्यक ऋषये नमः। शिरसि ।
oṃ bṛhadāraṇyaka ṛṣaye namaḥ । śirasi (touch the crown of the head)

ॐ अनुष्टुप् छन्दसे नमः । मुखे ।
oṃ anuṣṭup chandase namaḥ । mukhe (the face)

ॐश्री गोरक्ष देवताय नमः । हृदि ।
oṃ śrī gorakṣa devatāya namaḥ । hṛdi (the heart)

ॐ गो बीजाय नमः । गुह्ये ।
oṃ go bījāya namaḥ । guhye (the perineum)

ॐ विमला शक्तये नमः । पादयोः ।
oṃ vimalā śaktaye namaḥ । pādayoḥ (the feet)

ॐ हंसेति कीलकाय नमः । नाभौ ।
oṃ haṃseti kīlakāya namaḥ । nābhau (the navel)

करन्यासः । karanyāsaḥ । (the palm nyāsa)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय अङ्गुष्टाभ्यां नमः ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya aṅguṣṭābhyāṃ namaḥ । (connect two thumbs of your hands)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय तर्जनीभ्यां नमः ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya tarjanībhyāṃ namaḥ । (connect two index fingers)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय मध्यमाभ्यं नमः ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya madhyamābhyaṃ namaḥ । (connect the two middle fingers)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय अनामिकाभ्यां  नमः ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya anāmikābhyāṃ namaḥ । (connect two ring fingers)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय कनिष्ठिकाभ्यं नमः ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya kaniṣṭhikābhyaṃ namaḥ । (connect two little fingers)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय करतल-कर-पृष्ठाभ्यां नम: ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya karatala-kara-pṛṣṭhābhyāṃ namaḥ । (connect the back of the palms)

हृदयादिन्यासः । hṛdayādinyāsaḥ (nyāsa starts from the heart and etc.)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय हृदयाय नमः ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya hṛdayāya namaḥ । (touch the heart)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय शिरसे स्वाहा ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya śirase svāhā । (touch the head)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय शिखायै वषट् ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya śikhāyai vaṣaṭ । (touch the crown of the head)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय कवचाय हुं ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya kavacāya huṃ । (touch your shoulders)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय नेत्रत्रयाय वौषट् ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya netratrayāya vauṣaṭ । (touch three eyes)

ॐ ह्रीं श्रीं गों गोरक्षनाथाय सर्व विद्यापतये नमः अस्त्राय फट् ।
oṃ hrīṃ śrīṃ goṃ gorakṣanāthāya sarva vidyāpataye namaḥ astrāya phaṭ ।
(circle with your right hand above your head clockwise and hit the left palm with index and middle fingers three times)

अथ ध्यानम् । atha dhyānam (now is dhyāna)
(The text from the Kalpadruma Tantra)

निरञ्जनो निराकारो निर्विकल्पो निरामयः।
अगम्योऽगोचरोऽलक्ष्यो गोरक्षः सिद्धिवन्दितः॥
nirañjano nirākāro nirvikalpo nirāmayaḥ। 

agamyo’gocaro’lakṣyo gorakṣaḥ siddhivanditaḥ॥

Unsullied, devoid of image, free from vikalpas and disease, incomprehensible, unattainable, beyond of the symbols – Gorakṣa, revered by the siddhas.

समस्त रस भोक्ता यो यः सदा भोगवर्जित ।
सदा समरसो यश्च श्री गोरक्षनमोऽस्तु ते ॥
samasta rasa bhoktā yo yaḥ sadā bhogavarjita । 

sadā samaraso yaśca śrī gorakṣanamo’stu te ॥

To Him, who enjoys all races and who is always free from pleasures, who forever abides in samarasya, may there be worship to you, Śrī Gorakṣa!

हठयोग विधाता च मत्स्यकीर्ति विवर्धनः ।
योगिभिर् मनसा गम्यः श्री गोरक्षनमोऽस्तु ते ॥
haṭhayoga vidhātā ca matsyakīrti vivardhanaḥ । 

yogibhir manasā gamyaḥ śrī gorakṣanamo’stu te ॥

To the creator of haṭhayoga and to that who increased the fame of Matsyendra, the one whom yogis comprehend in their hearts, may there be worship to you, Śrī Gorakṣa!

सिद्धानाञ्च महासिद्धिः ऋषीणां च ॠषीश्वरः ।
योगीनाङ्चैव योगीन्द्रः श्री गोरक्षनमोऽस्तु ते ॥
siddhānāñca mahāsiddhiḥ ṛṣīṇāṃ ca ṝṣīśvaraḥ । 

yogīnāṅcaiva yogīndraḥ śrī gorakṣanamo’stu te ॥ 

To the great siddha among the siddhas, to the lord of the ṛṣi among the ṛṣis, to the lord of the yogis among the yogis, may there be worship to you, Śrī Gorakṣa!

विश्वतेजो विश्वरूपं विश्ववन्द्य सदाशिवः ।
विश्वनामा विश्वनाथः श्री गोरक्षनमोऽस्तु ते ॥
viśvatejo viśvarūpaṃ viśvavandya sadāśivaḥ । 

viśvanāmā viśvanāthaḥ śrī gorakṣanamo’stu te ॥

Universal light manifested in the image of the Universe, revered by all, Sadāśiva, who is called by all kinds of names, the lord of everything, may there be worship to you, Śrī Gorakṣa!

अनन्तलोकनाथश्च नाथनाथशिरोमणिः।
सर्वनाथसमाराध्यः श्री गोरक्षनमोऽस्तु ते ॥
anantalokanāthaśca nāthanāthaśiromaṇiḥ। 

sarvanāthasamārādhyaḥ śrī gorakṣanamo’stu te ॥ 

To the Lord of infinite worlds, the greatest (lit. “head precious adornment) of the Nāthas, to the Lord of all, to the one who is respected, may there be worship to you, Śrī Gorakṣa!

शून्यानाङ्च परं शून्यं परेषां परमेश्वरः ।
ध्यायताञ्च परं धाम श्री गोरक्षनमोऽस्तु ते ॥
śūnyānāṅca paraṃ śūnyaṃ pareṣāṃ parameśvaraḥ ।
dhyāyatāñca paraṃ dhāma śrī gorakṣanamo’stu te ॥ 

To the highest emptiness among the voids, to the Supreme Lord for others, to the highest state for the meditators, may there be worship to you, Śrī Gorakṣa!

Then you can practice japa using the mantras from the above tantras, they can be found here:


My perception of the right āsana

Over the years of yoga practice, I have developed my own definition of what the true āsana is. The right āsana is that, which leads to the interconnection of the two main dimensions of all. And through this in particular you will find explanations of any categories of āsanas. What those dimensions are, physical and spiritual or other explanations will be found for this, for everyone at their stage of practice, this can vary and can always be flexible. But, for any practitioner at any moment, this awareness of polarities must be total.

Yoga is the highest aim of a man

I always proceed from the fact that yoga, in its most essential form, is the prerogative of very few individuals. We can slowly go to it, this also includes our constant seeks and researches, but not everyone in this life reaches the point. Vyāsa, commenting on Patāñjali, gives such a definition of yoga योगः समाधिः  yogaḥ samādhiḥ“Yoga is samādhi”. We also find a great deal in the texts of the Nāthas and the most essential elements from yoga in diverse Tantras. But, we know that tantric practices have traditionally been largely kept in secret. So, what should be the attitude to yogic sādhanā, if it is the essence of tantric sādhanā? If you look at ancient yoga texts, secrecy is often mentioned there. The question is, what part of the yogic tradition and practice should be open and for whom, and which is closed? This is a very slippery moment, each guru, in one case or another, himself defines this boundary. With whom, when and what boundaries should be, and with whom should they not be at all, depends on each specific situation.

The importance of svara in the nātha sādhana

On higher levels of initiation and practice of tantrism, such as pūrṇābhiṣeka, medhā-sāmrājya and practices of upper āmnāya, there are methods of contemplation of Ardhanārīśvara. Also, such ritual as pañca-tattva is not usually practiced before śāktābhiṣeka dīkṣā, and this is especially true for higher initiations and āmnāyas. Such titles as left-handed or right-handed tantra have both symbolic and quite practical values, for instance, pātra with wine is taken by the left hand when we offer it to the ”inner fire” into the mouth of Kuṇḍalinī. The left part of the body is Śakti and the right is Śiva. Some tantrikas say that kaula sādhana begins where such dualistic methods as Patañjali yoga are ended. But the same could be said about nāthas and kaulasnātha sādhana begins where kaula sādhana ends. It has always been like that in India: the more recent endevour to continue something is more substantial than the previous one. That is why Gorakṣanātha is more honoured today than even Matsyendranātha, but this, of course, does not belittle the benefit and the authority of the latter. In the same way, for example, Vedanta – the completion of the Vedas, is not considered as something below the Vedas, but rather as its essence by either Vedantins or many other Hundu. Or, similarly, we couldn’t say that Vajrayana Buddhism is a simplification of Theravada, despite the fact that it had been developed later. Or, for instance, the fact that some cults of early female deities, like sapta and aṣṭa mātrikās have been transformed into such sophisticated cults as Trika, Kubjikā, Śrīvidyā and others, doesn’t make the latter less developed or less authoritative. And the most essential way was always the most secret, with a very careful selection of applicants for that kind of dedication and practice. The same could be said about nāthas. The phenomenon of svara-yoga is of tantric origin, but its basis is still yogic. In speaking of essence, by which we usually mean something that is closer to us as subjects, and also implying the involvement of the subjects in different degrees of the external process. That is why the practices with the body, breathing, with tracking how the breath is associated with the sun and the moon, how these two are related to the elements, tithis, grahas, nakṣatras and other aspects of both micro- and macrocosmos, are very great and subtle processes. But the most important thing is that they are all tied to the essence of it all, namely the yoga of the Sun and the Moon. In many books of both the medieval gurus of the Nāth Sampradāya and the present authors, we can very often find a description of the importance of svara-yoga and, of course, the practices of it. That can be called the basis of nātha-yoga, as its symbol is the Sun and the Moon, i.e. Śiva-Śakti saṃyukta.

The internal fire

It’s the time to expand the topic of “internal fire”. Accidentally, I discovered a very interesting description of the inner nāda source, which occurs in Bṛhadāraṇyaka Upaniṣad, one of the earliest Upaniṣadas. The śloka from there is also repeated in Maitri (Maitrāyaṇīya) Upaniṣad (2.6.).

बृहदारण्यक उपनिषद् । ५.११.९ ।
bṛhadāraṇyaka upaniṣad । 5.11.9 ।

अयमग्निर्वैश्वानरो योऽयमन्तः पुरुषे येनेदमन्नं पच्यते यदिदमद्यते तस्यैष
घोषो भवति यमेतत्कर्णावपिधाय शृणोति स यदोत्क्रमिष्यन्भवति नैनं घोषं शृणोति ॥

ayamagnirvaiśvānaro yo’yamantaḥ puruṣe yenedamannaṃ pacyate
yadidamadyate tasyaiṣa ghoṣo bhavati yametatkarṇāvapidhāya śṛṇoti sa
yadotkramiṣyanbhavati nainaṃ ghoṣaṃ śṛṇoti ॥

The fire, in the form of a universal being, is inside the living beings, thanks to it the food that is eaten is digested. He [a man], hears exactly that noise when he closes his ears. [However] he does not hear this sound when he dies.

Vaiśvānara is a very revered deity in the Vedas, much like Agni, and is often identified with him. It is also one of the deities that is recommended to perform dhyāna on in Yogayājñavalkya and Vasiṣṭha Saṃhitā. We can find many parallels with various yoga sources. For example, the following signs associated with purified nāḍis are listed in Haṭha Yoga Pradīpikā:

यदा तु नाडीशुद्धिः स्यात्तथा चिह्नानि बाह्यतः।
कायस्य कृशता कान्तिस्तदा जायेत निश्चितम् ॥१९॥

yadā tu nāḍīśuddhiḥ syāttathā cihnāni bāhyataḥ।
kāyasya kṛśatā kāntistadā jāyeta niścitam॥19॥

When the nāḍis are purified, then external signs appear: harmony and radiance of the body, the yogi has success beyond doubt.

यथेष्टं धारणं वायोरनलस्य प्रदीपनम्।
नादाभिव्यक्तिरारोग्यं जायते नाडिशोधनात् ॥२०॥

yatheṣṭaṁ dhāraṇaṁ vāyoranalasya pradīpanam ।
nādābhivyaktirārogyaṁ jāyate nāḍiśodhanāt ॥ 20 ॥

If the yogi can retain the life force (e.g. kumbhaka), then the radiance and inner fire are increasing. Having cleaned channels, the nāda sounds are heard and disease is overcome.

Of course, there are different types of agni in the body among which jaṭharāgni is considered particularly significant. However, the “health” concept is not the same from the common man and yogi’s point of view. Yogis do not set the goal of becoming just healthy, the goal for them is rather samādhi. Therefore, the ritual of internal and external fire for the gr̥hasthas, many tantrikas and for the sannyasins has different levels. The yogi awakens the internal fire only in the suṣumnā, “dying for the outside world.” Initially, nāda sounds appear with the fire and light, but with full realisation, even the smallest fluctuations of prāṇa-spandana are extinguished. The above-mentioned Maitri (Maitrāyaṇīya) Upaniṣad (6.22) says of two kinds of Brahman: Śābda Brahman, who manifests himself in the sound and Para Brahman, where the sound disappears.