Question

What do Scriptures tells us about Kundalini?

Answer

Chandogya Upanishad 8.6.6 and Katha Upanishad  2.16 speak the same thing:

यदा सर्वे प्रभिद्यन्ते हृदयस्येह ग्रन्थयः ।
अथ मर्त्योऽमृतो भवत्येतावद्ध्यनुशासनम् ॥ १५॥

शतं चैका च हृदयस्य नाड्य-
    स्तासां मूर्धानमभिनिःसृतैका ।
तयोर्ध्वमायन्नमृतत्वमेति
    विष्वङ्ङन्या उत्क्रमणे भवन्ति ॥ १६॥

When all the knots of Hridaya Granthi are cut down, mortal becomes an immortal and attains Brahman there. There are one hundred and one Nadis which emerge from Hridaya (heart) one Nadi goes out piercing the head.  Going up through that, one attains immortality; the others serve for departing in different ways.

Now, a question comes here whether the Nadis mentioned here are Arteries of heart where blood moves or Nãdis of Yoga where Prana moves. Prashna Upanishad 3.6 makes it clear:

हृदि ह्येष आत्मा । अत्रैतदेकशतं नाडीनं तासां शतं शतमेकैकस्या द्वासप्ततिर्द्वासप्ततिः प्रतिशाखानाडीसहस्राणि भवन्त्यासु व्यानश्चरति ॥ ६॥

III-6: This self (i.e. the subtle body) is surely in the Hridaya (heart). There are a hundred and one Nãdis. Each of them has a hundred (division). Each branch is divided into seventy-two thousand sub-branches. Among them moves Vyana.

As the Prashna Upanishad clearly says 'among them moves the Vyana' so it is clear that Prana moves in these Nadis (and these are not Arteries).

Now, we have to find which is that one Nãdi which is such important. The Maitryaniya Upanishad makes it clear:

  1. And thus it has been said elsewhere: The artery, called Sushumna, going upwards (from the heart to the Brahmarandhra), serving as the passage of the Prâna, is divided within the palate. Through that artery, when it has been joined by the breath (held in subjection), by the sacred syllable Om, and by the mind (absorbed in the contemplation of Brahman), let him proceed upwards, and after turning the tip of the tongue to the palate, without using any of the organs of sense, let greatness perceive greatness. From thence he goes to selflessness, and through selflessness he ceases to be an enjoyer of pleasure and pain, he obtains aloneness (kevalatva, final deliverance).

So, now it becomes clear that the 'Nãdi' which leads towards immortality is Sushumna.

What contains outside the world is also contained inside our body. Regarding this Chandogya Upanishad 8.1 states:

VIII-i-1: Om. Now, in this city of Brahman, there is a mansion in the shape of a small lotus; in it is a small inner Akasa. What is within that, that should be sought; that indeed, one should desire to understand.

VIII-i-2-3: If the disciples should say to him, ‘In this city of Brahman in which is a small mansion in the shape of a lotus and in the small inner Akasa within – what is it that lies there which should be sought, which one should desire to understand ?’ – he should say in reply, ‘As large indeed as is this Akasa, so large is that Akasa in the heart. Within it, indeed, are contained both heaven and earth, both fire and air, both the sun and the moon, lightning and the stars. Whatever there is of him in this world and whatever is not, all that is contained within it.’

Now, the Yoga Kundalini Upanishad states that the realisation of this is possible through Kundalini Yoga:

  1. Then he sees the whole universe in his body as not being different from Atman. This path of the Urdhva-Kundalini (higher Kundalini), O chief of Kings, conquers the macrocosm. [Yoga Kundalini Upanishad]

These are some of the concepts of Kundalini Yoga. Regarding exactly what is Kundalini is, it is Shakti which is present in every Nadi of our body and in personified Form Kundalini is present in Muladhara Chakra (which I discuss here). Regarding this Lalita Sahasranama of Brahmanda Purana states:

तडिल्लता समरुचि: षट्चक्रोपरि संस्थिता ।
महासक्ति: कुण्डलिनी विसतन्तु तनीयसी ।।

Bright  like Lightning you reach above the Six chakras. You are Kundalini the great energy which is subtle in nerves.

Detailed concepts of Kundalini is found in Yoga Upanishads like:

Mandala Brahmana Upanishad states:

Taraka is Brahman which being in the middle of the two eyebrows, is of the nature of the spiritual effulgence of Sachchidananda. The (spiritual) seeing through the three Lakshyas (or the three kinds of introvision) is the means to It (Brahman). Susumna which is from the Muladhara to Brahmarandhra has the radiance of the sun. In the centre of it, is Kundalini shining like Crores of lightning and subtle as the thread in the lotus-stalk. Tamas is destroyed there. (Mandala Brahmana Upanishad)

The Sandilya Upanishad states:

  1. Then Sandilya questioned Atharvan thus: "By what means are the Nadis purified ? How many are they in number ? How do they arise ? What Vayus (vital airs) are located in them ? What are their seats? What are their functions? Whatever is worthy of being known in the body, please tell me". To that Atharvan replied (thus): "This body is ninety-six digits in length. Prana extends twelve digits beyond the body. He who through the practice of Yoga reduces his Prana within his body to make it equal to or not less than the fire in it becomes the greatest of the Yogins. In men, the region of fire which is triangular in form and brilliant as the molten gold is situated in the middle of the body. In four-footed animals, it (fire) is quadrangular. In birds, it is round. In its (the region of life’s) centre, the purifying, beneficial and subtle flame is situate. Two digits above the anus and two digits below the sexual organ is the centre of the body for men. For four-footed animals, it is the middle of the heart. For birds, it is the middle of the body. Nine digits from (or above) the centre of the body and four digits in length and breadth is situated an oval form. In its midst is the navel. In it, is situated the Chakra (viz., wheel) with twelve spokes. In the middle of the Chakra, the Jiva (Atman) wanders, driven by its good and bad deeds. As a spider flies to and fro within a web of fine threads, so Prana moves about here. In this body, the Jiva rides upon Prana. Lying in the middle of the navel and above it, is the seat of Kundalini. The Kundalini Sakti is of the form of eight Prakritis (matter) and coils itself eight ways or (times). The movement of Vayus (vital airs) checks duly the food and drink all round by the side of Skandha. It closes by its head (the opening of) the Brahmarandhra and during the time of (the practice of) Yoga is awakened by the fire (in the Apana); then it shines with great brilliancy in the Akasa of the heart in the shape of wisdom. Depending upon Kundalini which is situated in the centre, there are fourteen principal Nadis (viz.,) Ida, Pingala, Susumna, Sarasvati, Varuni, Pusha, Hastijihva, Yasasvini, Visvodhari, Kuhuh, Sankhini, Payasvini, Alambusa and Gandhari. Of them, Susumna is said to be the sustainer of the universe and the path of salvation. Situated at the back of the anus, it is attached to the spinal column and extends to the Brahmarandhra of the head and is invisible and subtle and is Vaishnavi (or has the Sakti force of Vishnu). On the left of Susumna is situated Ida and on the right is Pingala. The moon moves in Ida and the sun in Pingala. The moon is of the nature of Tamas and the sun of Rajas. The poison share is of the sun and the nectar of the moon. They both direct (or indicate) time and Susumna is the enjoyer (or consumer) of time. To the back and on the side of Susumna are situate Sarasvati and Kuhuh respectively. Between Yasasvini and Kuhuh stands Varuni. Between Pusha and Sarasvati lies Payasvini. Between Gandhari and Sarasvati is situated Yasasvini. In the centre of the navel is Alambusa. In front of Susumna there is Kuhuh, which proceeds as far as the genital organ. Above and below Kundalini is situated Varuni, which proceeds everywhere. Yasasvini which is beautiful (or belonging to the moon), proceeds to the great toes. Pingala goes upwards to the right nostril. Payasvini goes to right ear. Sarasvati goes to the upper part or the tongue and Sankhini to the left ear, (while) Gandhari goes from the back of Ida to the left eye. Alambusa goes upwards and downwards from the root of the anus. From these fourteen Nadis, other (minor) Nadis spring; from them springing others and from them springing others; so it should be known. As the leaf of the Asvattha tree (ficus religiosa) etc., is covered with minute fibres so also is this body
    permeated with Nadis.

The Sandilya Upanishad also states:

  1. Having by contraction opened the door of Kundalini, one should force open the door of Moksha. Closing with her mouth the door through which one ought to go, the Kundalini sleeps spiral in form and coiled up like a serpent. He who causes this Kundalini to move - he is an emancipated person. If this Kundalini were to sleep in the upper part of the neck of any Yogin, it goes towards his emancipation. (If it were to sleep) in the lower part (of the body), it is for the bondage of the ignorant. Leaving the two Nadis, Ida and the other (Pingala), it (Prana) should move in the Susumna. That is the supreme seat of Vishnu. One should practise control of breath with the concentration of the mind. The mind should not be allowed by a clever man to rest on any other thing.

Similarly the Yoga Kundalini Upanishad states:

  1. The Sakti (mentioned above) is only Kundalini. A wise man should take it up from its place (Viz., the navel, upwards) to the middle of the eyebrows. This is called Sakti-Chala.

  2. In practising it, two things are necessary, Sarasvati-Chalana and the restraint of Prana (breath). Then through practice, Kundalini (which is spiral) becomes straightened.

    9-10(a). Of these two, I shall explain to you first Sarasvati-Chalana. It is said by the wise of old that Sarasvati is no other than Arundhati. It is only by rousing her up that Kundalini is roused.

    10(b)-11(a). When Prana breath is passing through (one’s) Ida (left nostril), he should assume firmly Padma-posture and should lengthen (inwards) 4 digits the Akasa of 12 digits.

    11(b)-13(a). Then the wise man should bind the (Sarasvati) Nadi by means of this lengthened (breath) and holding firmly together (both his ribs near the navel) by means of the forefingers and thumbs of both hands, (one hand on each side) should stir up Kundalini with all his might from right to left often and often; for a period of two Muhurtas (48 minutes), he should be stirring it up fearlessly.

    13(b)-14. Then he should draw up a little when Kundalini enters Susumna. By this means, Kundalini enters the mouth of Susumna. Prana (also) having left (that place) enters of itself the Susumna (along with Kundalini). (Yoga Kundalini Upanishad)

It further states:

  1. When Apana is raised up and reaches the sphere of Agni (fire), then the flame of Agni grows long, being blown about by Vayu.

    44-45(a). Then Agni and Apana come to (or commingle with) Prana in a heated state. Through this Agni which is very fiery, there arises in the body the flaming (or the fire) which rouses the sleeping Kundalini through its heat.

    45(b)-46. Then this Kundalini makes a hissing noise, becomes erect like a serpent beaten with stick and enters the hole of Brahmanadi (Susumna). Therefore Yogins should daily practise Mulabandha often.

Similarly Devi also speaks about knowledge of Kundalini and Chakras in Devi Bhagvatam in this chapter.

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