Ida is said to be the flow of Bagirathi (Ganga). Pingala is the flow of Yamuna. The Nadi which flows through the middle of the brow is Saraswathi. In the above quoted verse the three Nadies are symbolised as three psychic rivers, viz, Ganga, Yamuna and Saraswathi. These rivers should not be confounded with terrestrial rivers of the same names. Some knowledge about these three psychic rivers will be useful in the understanding and the practice of Yoga.

Hatha Yoga describes Ida as moon, the symbol of the mind and Pingala as Sun, Symbol of soul (Atman). The moon has no light of its own. It has to depend on Sun for its light. In the same manner the mind has no light of its own apart from what it gets from the soul or life principle within. Idom in Dravidian means, a place, a spot and may even mean the wide space. This word Idom is derived from Ida which is the Kala that has brought about the phenomenal world which is also called by the name of Bhaga. Ratham means flow. So Bhagiratham means the flow of phenomenal world from its causal point the jeeva or life principle. This flow is symbolised as Ganges (Ganga) flowing down to earth from the head of Shiva. The legendary account of king Bagiratha bringing down the Ganges from Akasa (heavens) in the Devi Bhagavatham should be understood in this light, to make the legend a purposeful study. Ida is to be understood as the creative force which made the world apparent to the senses and not as the flow of breath through the left nostril.

The word Pingala is misunderstood as the flow of breath through the right nostril. Pingala is also a word of Dravidian origin, 'Pin' means rearward. 'Kala' comes from the root 'Kal' meaning Air. So Kala means the force of air or the force of life energy. Pinkalai therefore is indicative of the receding or retracting force that withdraws the mind towards sushumna or seat of soul. Pingala is only a corruption of the word Pinkalai. It is also significant that the Sun which is symbol of the soul is also known by the name Pingala. Amarakosa mentions Yamuna as Surya Thanaya (daughter of Sun) which is also significant. In mystic language, Ida the outgoing force is symbolised by sound symbol 'Ham' and the incoming force by sound symbol 'Sam'. Both put together becomes 'Hamsam' the cosmic swan the vehicle of Brahma the creator, a very meaningful expression.