The scriptures try to explain the spiritual realm by using worldly analogy. If this was not done, it may be difficult for us to appreciate and understand. Saint Pipa, one of whose hymns is incorporated in Guru Granth Sahib, was a prince who renounced his throne in search of spiritual solace. Saint Pipa says:
The One who pervades the Universe also dwells in the body,
Whoever seeks Him, finds Him there.
In order to better understand the human body, and its internal composition, including the thought process, the scriptures use examples from the outer world. We therefore learn of the concept of Triveni, the spot where the three rivers meet. In the Indian sub-continent, the rivers are Ganga, Yamuna, and Saraswati, and the confluence is a holy place, promising redemption. We are then led towards an understanding of the body, with the entire nervous system as a knowledge gathering system, with the nerves being the rivers of knowledge. The ida represents Ganga (nerves from the left side), the pingala represents Yamuna (nerves from the right side), and sushmana as Saraswati, the spinal cord. All these body rivers travel up and meet in the brain, the holy sangam, or confluence. Saint Baini says:
The energy channels of the Ida, Pingala and Sushmana: these three dwell in one place.
This is the true place of confluence of the three sacred rivers: this is where my mind takes its cleansing bath.
As a guide to the devotee, Guru Granth Sahib says:
One who calls himself a Sikh of the Guru, shall rise in the early morning hours and meditate on the Lord’s Name.
Upon arising early in the morning, he is to bathe, and cleanse himself in the pool of nectar.
The devotee travels inwards across the ida, pingala, and shushmuna, to arrive at the confluence, the pool of nectar present inside each one of us, and is one with Him.