पृथिव्यप्तेजोवाय्वाकाश श्रोत्रत्वक्जिह्वाघ्राण वाक्पादपाणिपायूपस्थानि मनोविकाराः कामाकर्षिण्यादि षोडशशक्तयः॥(Bhāvanopaniṣad 10)

pṛthivyaptejovāyvākāśa śrotratvakjihvāghrāṇa vākpādapāṇipāyūpasthāni manovikārāḥ kāmākarṣiṇyādi ṣoḍaśaśaktayaḥ ||

This verse is about the second āvaraṇa, known as sarvāśā-paripūraka cakra. The sixteen powers that are being discussed in this verse refer to sixteen subtle elements of the body. Sixteen śakti-s (devi-s) represent five principal elements - earth, water, fire, air, ākāśa (another interpretation is that they represent five prāṇa-s); five organs of perception – ears, skin, eyes, tongue, nose; five organs of action – mouth, feet, hands, organs of excretion and procreation. Thus five mahābhūta-s, five jñānendriya-s and five karmendriya-s make fifteen elements. If we add mind (manas), then we get sixteen śakti-s, each śakti presiding over one of the above sixteen powers. Mind and indriya-s (faculty of sense) are purified here in saṁhāra krama (the process of liberation and ultimate merger unto Śiva). Here all the embedded thoughts are completely annihilated by these sixteen devi-s. In particular, subconscious mind is purified here resulting in no-dream state. The devotee who worships this āvaraṇa mentally gets his subtle body cleansed by these sixteen devi-s. It can also be said that the sixteen kalā-s of the moon in their individual capacities purify the subtle body of the aspirant. There is a strong relationship between these sixteen śakti-s and sixteen tithi nityā devi-s. The process of purifying a devotee continues in the second āvaraṇa. During sṛṣṭi krama (during creation; creation happens from the innermost triangle and the bindu), these sixteen sixteen kalā-s of the moon represent Vimarśa (Śakti) aspect of Prakāśa (Śiva). They work on the subtle body known as manas or mind (manomayakośa). Each of these devi-s have different powers and during creation, powers of one or more than one devi work on a person during birth and that power manifests in him as he grows. During the reversal process, all such powers are withdrawn while cleansing his mind.

vacanādānagamananavisargānanda hānopādanopekṣākhya buddhayo'naṅgakusumāddyāṣṭau ||

वचनादानगमननविसर्गानन्द हानोपादनोपेक्षाख्य बुद्धयोऽनङ्गकुसुमाद्द्याष्टौ॥ (Bhāvanopaniṣad 11)

This verse is about third āvaraṇa, which is also known as sarvasaṁkṣobhaṇa cakra. The mind that was cleansed in the previous āvaraṇa is not complete. Still there are some traces left in the mind. But the mind needs to be completely purified before liberation, as liberation is possible only through mind. Mind is often afflicted with non-essential ego. There are two types of egos. One is essential ego, which is necessary for our existence. Another is non-essential ego, which is known as pride or self-boasting.  

Let us understand this with examples. In a yogi, only non-essential ego alone prevails. He never talks about himself. If one is truly a realized person, he will not boast himself. There is no need for him. Why should he go and tell someone that he is a realized person. He does not like that. This is the stage where non-essential ego is completely annihilated. Annihilation of non-essential ego is directly related to one’s spiritual advancement. Let us take an example of a self proclaimed yogi. He will only try to project himself as a realized person for reasons best known to him. A Self-realized person can never be lured with money. Therefore, desire for material gains and ego are also directly related.  Liberation cannot be bought with money and can be attained only with the guidance of a Guru coupled with dedication and perseverance to do sādhana. Even for a fully realized person, traces of non-essential ego will continue to prevail*. There are only very few exceptions like Ramana Maharishi. There is every likely hood that these traces could sprout and grow to unmanageable proportions, which could be disastrous.

The traces of non-essential ego if any will be removed in this āvaraṇa*. After purifying his mind, he aspirant begins to develop detachment from the material world. These eight āvaraṇa devi-s work on puryaṣṭaka (eight constituents of the body) and remove their afflictions if any. Liberation can be attained only by those who have conquered puryaṣṭaka. Puryaṣṭaka consists of the following eight- 1) five organs of action (karmendriya-s), 2)  five organs of senses (jñānaendriya-s), 3) antaḥkaraṇa (four in numbers - manas, buddhi, cittam and ahaṃkāra or ego), 4) five prāṇa-s (prāṇa, apāṇa, etc), 5) five elements (ākāśa, air, etc) 6) desire, 7) ignorance and 8) karma. The total components of   puryaṣṭaka are twenty seven and with this, the attributes of Śiva is added, takes the total to twenty eight. The mūla mantra of Mahā Gaṇapati is twenty eight.  When all the twenty seven components of puryaṣṭaka are destroyed, it leads to attributes of Śiva. The attributes of Śiva (saguṇa Brahman) leads to pure Śiva or nirguṇa Brahman (Śiva without attributes). Saguṇa Brahman (Vimarśa aspect of Śiva, known as Śakti) is often realized in the form of Bliss (Śakti is always known for Her Ānanda; in Trika philosophy, She is known as Ānanda Śakti). When we merge into Śiva, even this Bliss is also annihilated, as Bliss is related to mind. Third cleansing process happens in this āvaraṇa.

The mind that is often agitated gets calmed down at the end of this āvaraṇa. Agitations prevail only if the mind is filled with desires and attachments. When desires and attachments are removed, the mind becomes calm. This process is done in this āvaraṇa, as at the time of liberation, mind should be completely free of any thought processes and this process is being done through these eight āvaraṇa devi-s.