What is left in the old books: what can be taught, what is only worth knowing

The texts file Kaki with the cooling group, and state its practical use plainly: it balances the body temperature again when practised after the heating breaths. Which means you have one more cooling option alongside Sheetali and Sheetkari — useful when the room contains someone who cannot roll their tongue (Sheetali requires rolling the tongue into a tube, and roughly a third of people cannot, for inherited reasons).

The reason is purely mechanical: breathing in through the mouth bypasses the filtering and warming function of the nose. So the texts forbid practising it in polluted air or in weather that is too cold. For a class here: avoid a room right on a dusty road, avoid the really cold days. And keep the eyes from tiring — the gazing at the nose tip must never be strained.

That is the list exactly as the texts give it. In addition, anyone with diabetic retinopathy, or who has recently had cataract surgery, a lens implant, or eye surgery of any kind — must not practise it without a teacher present. Most of this concerns the eyes, because the practice holds the gaze at the nose tip. In a full room, say it briefly: “anyone with an eye condition or recent eye surgery, drop the gazing at the nose tip and just close your eyes and breathe.”

The name means “swooning” or “fainting”. Per the texts: sit steadily in meditation, watch the breath until it is slow and deep; apply khechari mudra (the tongue curled up to the palate), then breathe in slowly through both nostrils in the Ujjayi manner while gently tipping the head back; apply shambhavi mudra (the eyes turned up to the point between the eyebrows); straighten the arms, lock the elbows, press the hands down on the knees; hold the breath in for as long as it is comfortable; then breathe out, release the hands, close the eyes, bring the head upright, and release for a few seconds.

That is not a hedge of mine — it is the precaution printed in the book. This technique deliberately induces a light swooning sensation. The texts also say clearly: stop the moment that sensation appears; the destination is a light-headed feeling, NOT loss of consciousness. Contraindications: heart conditions, high blood pressure, epilepsy, brain disorders, and atherosclerosis of the carotid or basilar arteries.

Think about it practically: in a class of twenty, you do not know who has carotid atherosclerosis. And this practice both tips the neck back and holds the breath — exactly the two things that act on the blood vessels of the neck. A professional is someone who knows this practice exists, can describe it, and does not bring it into a class. When a student asks, the correct answer is: “That practice does exist, and the books describe it carefully, but it needs a teacher one to one — we don't do it in this class.”

The Gheranda Samhita divides holding the breath (kumbhaka) into eight kinds: Sahita, Suryabheda, Ujjayi, Sitali, Bhastrika, Bhramari, Moorchha, Kevali. You have learned the six in the middle, and understood Kevala in Lesson 18. That leaves Sahita — meaning “accompanied”, that is, a deliberate hold, the counterpart of Kevala, which arrives of itself.

Per the text: Sahita has two kinds — holding the breath with the repetition of a seed syllable (bija mantra) is called Sagarbha; holding without any repetition is Nirgarbha. That is the whole difference. For your teaching: Nirgarbha is every held-breath practice you have done — breathe in, hold, breathe out, counting the rhythm. Sagarbha is when a sound or mantra is repeated silently during the hold, which carries a religious colour — best not brought into a general yoga class unless students ask for it themselves.

A trick of the trade: what makes Sagarbha effective is that the mind has something to hold on to during the hold — so it is not counting the seconds anxiously. You can take exactly that principle and leave the religion out: have students count silently and steadily, or hum a very quiet “mmm” in the mind. You keep the benefit and avoid matters of belief in a full room.

Plavini sits in the Hatha Yoga Pradipika — among that book's eight kumbhakas. The old description: the practitioner swallows air into the digestive tract until the belly is full, to the point of being able to float on the surface of water (“plavini” comes from the word for floating). It does not appear in Asana Pranayama Mudra Bandha — the standard practical manual of the Bihar school. The fact that a modern teaching text drops a practice from the old books entirely is itself the answer to “should it be taught?”.

Unlike every practice you have learned (all of which work with the lungs), Plavini puts air into the digestive tract. That is reason enough for a modern yoga teacher neither to practise nor to teach it. Know the name, know which book it is in, know why you do not teach it — that is enough, and it is professional.

Khechari mudra (the tongue lock) appears in the Moorchha practice above. At a safe introductory level it is simply curling the tongue back so the tip touches the upper palate and holding it comfortably while breathing — that much you can use; it reduces swallowing and keeps the jaw soft. The deeper stages of Khechari in the old books involve lengthening the tongue over many months — outside the scope of a yoga class, and no business of yours.

1. Do the texts require a teacher present? If yes (as with Moorchha) → not for a full room.
2. Does the exclusion list contain conditions I CANNOT know about in a full room? (carotid atherosclerosis, glaucoma…) → not for general teaching.
3. Does it act outside the lungs? (swallowing air into the stomach, taking water through the nose) → keep it separate, not for a full room.
4. Do the modern manuals keep it? If the standard text drops it entirely (as with Plavini) → drop it too.

Teachable to a full room: natural / belly / chest / full breathing, Ujjayi, Nadi Shodhana, Sama Vritti, Viloma, Bhramari, Sheetali, Sheetkari, Kaki, Udgeeth, Simha, 4-7-8, Chandra / Surya Bhedana (a small dose), Kapalbhati the air way, Bhastrika (a small dose, carefully screened).
One to one, or a small screened group: Agnisara, Nauli stage one, held breaths with bandha, Maha Bandha.
Only worth knowing, not taught: Moorchha, Plavini, the deep stages of Khechari, the two water ways into Kapalbhati.

At the end of twenty lessons, what you take away is not “knowing more practices than other people”, but knowing how to choose: the right practice, the right person, the right moment, the right dose — and knowing where to stop. A good teacher is remembered for never having harmed anybody, not for being able to teach the rarest practice.