The Siva Samhita discusses the four stages of avastha in pranayama. We learn from http://www.srimayogaschool.com.au/pranayama-info.html
1. Arambha avastha "is entered when the practitioner has performed Nadi-sudhi or purification of channels of energy in the body.
2. Ghata avastha is acquired by constant practice of the retention of breath.
3. Parichaya avastha is attained when vayu or breath pierces the kundalini, along with agni through thought, and enters the sushumna along with prana.
4. Nishpati avastha, "the fourth and final stage is where the practitioner reaches a state of perfect bliss. At this point, he is able to perform Kevala kumbhaka or sahaja kumbhaka - holding the breath with no particular state of respiration in consideration. Having destroyed all the seeds of karma, such a yogi feels neither hunger nor thirst, nor sleep nor swoon and drinks the nectar of immortality. He becomes absolutely independent, free from all diseases, decay and old age, and can move anywhere in the world. No longer in need of any yogic practice, he enjoys the bliss of samadhi."
From Swami Sivananda’s teachings on prana and pranayama at http://sivanandaonline.org/public_html/?cmd=displaysection§ion_id=1305 and an exact copy at http://www.yogamag.net/archives/2009/haug09/stages.shtml we gain further enlightenment on this subject of avastha.
1. Coming to pranayama is Arambha avastha.
2. Ghata avastha is when one moves into retention of the breath called kumbhaka or cessation of breath called pratyahara where withdrawal of the senses is arrived at by bringing the attention inwards towards the breath, observing it without trying to control it. By doing this, connection with the external senses and stimuli are all gradually severed.
3. Parichaya avastha is when "prana with Vayu or breath, and along with agni through thought, pierces the kundalini, and enters the Sushumna." Karma is destroyed by the double-edged sword of Pranavam Aum that prevails within and "Kaya-vyuha, a mystical process of taking various bodies to exhaust all previous karmas without the necessity of being reborn." He gains command over the five elements by the practice of the five tattwa dharanas or forms of concentration. Hence he conquers and masters the five elements that are the source of creation.
4. Nishpatti avastha is the state of consummation between God and Man. "Having destroyed all the seeds of karma", he sustains and lives on Prana, and "drinking the nectar of immortality", hence "enjoying the bliss of samadhi" that equates to being liberated in a sense.
From https://www.intuitiveflow.com/spiritual-development/ we learn the following.
2. Ghata avastha is when one moves into retention of the breath called kumbhaka or cessation of breath called pratyahara where withdrawal of the senses is arrived at by bringing the attention inwards towards the breath, observing it without trying to control it. By doing this, connection with the external senses and stimuli are all gradually severed.
3. Parichaya avastha is when "prana with Vayu or breath, and along with agni through thought, pierces the kundalini, and enters the Sushumna." Karma is destroyed by the double-edged sword of Pranavam Aum that prevails within and "Kaya-vyuha, a mystical process of taking various bodies to exhaust all previous karmas without the necessity of being reborn." He gains command over the five elements by the practice of the five tattwa dharanas or forms of concentration. Hence he conquers and masters the five elements that are the source of creation.
4. Nishpatti avastha is the state of consummation between God and Man. "Having destroyed all the seeds of karma", he sustains and lives on Prana, and "drinking the nectar of immortality", hence "enjoying the bliss of samadhi" that equates to being liberated in a sense.
From https://www.intuitiveflow.com/spiritual-development/ we learn the following.
1. In Arambha Avastha "They start experiencing Prana moving throughout their body and their senses of perception are enhanced."
2. In Ghata Avastha "The seed is decaying. It is a time of change and disruption. The yogi/ni is experiencing some resistance and pain whether is mental, physical or emotional. Their whole foundation is shaken or even collapsing as they are shaken to the core mentally and emotionally. The life that they have been living has outgrown its form. They go through a psychic death so that life force energy can be released in a new form." True to these words Agathiyar told me that I had stagnated at Svadisthana and came to give certain techniques to rise up further. Similarly, he gave others certain practices and techniques too. We are seeing a sudden urgency as Agathiyar takes the whip and disciplines us, hastening us, and asking to show some seriousness in our practices.
3. In Paricaya Avastha we are told that "The seed is now germinating. There is a release of tension and uncertainty. Profound changes and new qualities are emerging. It is a time of deliverance. It is the beginning of a new path. Resistance is dispersed and rectification is happening naturally and easily." We have to wait and see these changes take place as we settle and promise to diligently follow Agathiyar's instructions on the Yogic practices.
4. Nispatti Avastha is where "The blossoming occurs. A new life begins filled with contentment and harmony. The yogi/ni is detached and the Sukha and Duhkha don’t affect them anymore. The yogi/ni submits to the will from above. They are no longer bound by old patterns and attain freedom and liberation." Again we need to wait and see if we qualify and blossom into this state.
2. In Ghata Avastha "The seed is decaying. It is a time of change and disruption. The yogi/ni is experiencing some resistance and pain whether is mental, physical or emotional. Their whole foundation is shaken or even collapsing as they are shaken to the core mentally and emotionally. The life that they have been living has outgrown its form. They go through a psychic death so that life force energy can be released in a new form." True to these words Agathiyar told me that I had stagnated at Svadisthana and came to give certain techniques to rise up further. Similarly, he gave others certain practices and techniques too. We are seeing a sudden urgency as Agathiyar takes the whip and disciplines us, hastening us, and asking to show some seriousness in our practices.
3. In Paricaya Avastha we are told that "The seed is now germinating. There is a release of tension and uncertainty. Profound changes and new qualities are emerging. It is a time of deliverance. It is the beginning of a new path. Resistance is dispersed and rectification is happening naturally and easily." We have to wait and see these changes take place as we settle and promise to diligently follow Agathiyar's instructions on the Yogic practices.
4. Nispatti Avastha is where "The blossoming occurs. A new life begins filled with contentment and harmony. The yogi/ni is detached and the Sukha and Duhkha don’t affect them anymore. The yogi/ni submits to the will from above. They are no longer bound by old patterns and attain freedom and liberation." Again we need to wait and see if we qualify and blossom into this state.
But before we embark on pranayama or control of the breath, we need to start at stage one, Arambha Avastha, clearing the nadis through Naadi Shodhanam or Anuloma-Viloma or Naadi Shuddhi or Alternate Nostril Breathing.
The word "naadi" means "nerves". In fact, in yoga the term naadi is applied to psychic channels associated with the flow of prana (vital life force). According to some ancient texts, there are 72,000 such naadis in a human system. The words "shuddhi" or "shodhanam" both mean "cleansing" or "purification". So the term "naadi shuddhi" literally means cleansing of the subtle nervous system. A clean naadi system allows free flow of prana which helps bring more vitality and energy to the system. The effect or fruit of Pranayama is Udghata or awakening of the sleeping Kundalini. In the Kundalini system of yoga, balancing the breath between the two nostrils implies balancing the Ida and Pingala naadis. When these two naadis are balanced, then the prana (vital energy) can flow through the central channel of energy called "sushumna naadi" thus clearing the passage for the rising of the Kundalini Shakti.(Source: http://www.srimayogaschool.com.au/pranayama-info.html )
We are told that the idea of pranayama or controlling the breath is to shorten its length. "The length of the breath is respectively 12, 16, 4, 8, 0 fingers’ breadths according to the Tattvas - Prithvi, Apas, Tejas, Vayu or Akasa (earth, water, fire, air or ether)." (Source: http://www.srimayogaschool.com.au/pranayama-info.html). The practitioner of pranayama slowly and progressively brings the breath from 12 units where it is external and obvious, to move within, where it stays in Kevala Kumbhaka, almost stationary and resting in 0. For this to be possible and attainable, one has to learn to sit quietly. It is said that when once a seeker asked Bhagawan Ramana for instruction, Ramana told him to face the wall and sit quietly. When Lord Muruga came to save Arunagiri who jumped off the temple tower, he gave him the instruction to sit quietly. Lord Muruga, Agathiyar and Ramalinga Adigal, have asked us to sit quietly and go within. In coming to Yoga we are repeatedly told to sit still. Why is this so? Kireet Joshi explains the reasons beautifully in his blog at http://kireetjoshi.in/books/teachers-training/mystery-and-excellence-on-the-human-body/arambha-avastha.
In the technique of Asanas, the body is taught to remain immobile in certain special postures. Why immobile? Because the usual restlessness of our body is just a sign that it is unable to hold even a limited amount of energy that enters into it. It immediately wants to dissipate it. By remaining absolutely still in the most difficult of prescribed postures, the body is taught to retain the life energy and to regulate it.
Having us sit still is solely for the conservation of energy that shall be redirected for other use within. The various asanas are "meant to alter the relation of the physical energy in the body to the earth energy. Consequently, the body tends to get something of the qualities of the subtle body." Kireet extols the role of the body as "It is known and experienced as a living symbol, a powerful and sacred yantra which can connect us with our subtle body, with the universal energy, with the Divine." He adds, "Hatha Yoga gives us a key to discover the subtle body behind the gross body. It also gives us the knowledge and experience of the centers of the subtle body, each one of which connects a certain level of consciousness and energy with its corresponding universal plane of consciousness and energy."