In plain words
If there were no Manas at all, there would be no man at all. Good qualities such as śama and dama, inquiry into the Ātma and the anātma, examination of what is eternal and what is transient: the coming together of such sacred qualities is what is called pure Manas. Through qualities such as attachment, hatred, envy, Ahaṅkāra and ostentation, it is spoken of as impure Manas. The attainment of Jñāna, too, comes only to one who has purity of citta. ‘Jñānādevatu kaivalyaṃ.’ The state of that Kaivalya is what is called ‘the Haṃsa principle’. ‘Ha’ is the sign of the Paramātma principle. ‘Sa’ is the sign of Prakṛti, which is made of name and form. The point between the two is the principle of identity that harmonises the two. In short, the right meaning of the word Haṃsa is precisely the oneness of Paramātma and Prakṛti. This same thing is also called the contemplation of the oneness of the jīva and Brahman.
Here the Haṃsa, joined with the vital air, moves through all the seven nāḍīs in the body 21,600 times a day. Day and night this Haṃsa keeps moving, by ascent and descent, in the iḍā and piṅgaḷā nāḍīs. Iḍā, piṅgaḷā. ‘Iḍā’ means the sun, and ‘piṅgaḷā’ means the moon. ‘Candramā manaso jātaḥ cakṣo sūryo ajāyata’: so they call the principle of Manas the moon, and the radiant principle of our eyes the sun. On account of this very movement of the Haṃsa it has the name Praṇava, the name Haṃsa Gāyatrī, and the name contemplation of the oneness of jīva and Brahman. Tāraka is another name. They have long been giving these out as synonyms.
The six cakras
All the threads of these nāḍīs become one in the place of the suṣumnā. It begins in the Mūlādhāra and keeps travelling up to the Sahasrāra. These are what they have long called the six cakras. They are the Mūlādhāra, the Svādhiṣṭhāna, the Maṇipūraka, the Anāhata, the Viśuddha, the Ājñā-cakra and the Sahasrāra. Of these seven, each one has its own characteristic of Prakṛti.