In the lotus-like heart is the Self–the Supreme Self, the Atman. The heart has 101 arteries. Each one of them has a hundred smaller branches. To each of these smaller branches, belong 72,000 sub-branching arteries; within them, moves the diffused breath, the Prana known as Vyana.
Now, rising upward through one of these arteries called the Sushumna Nadi, the ascending-breath–Udana–in consequence of good work leads to the good world, in consequence of evil leads to the evil world, in consequence of both good and evil leads to the world of men. Wherever this breath is diverted–up or down, higher or lower–finally decides the fate of the human being.
Then, the Rishi connects the breaths together in the human body with the eternal energy of the visible Universe. The Sun verily rises as the external Prana, for it is that which helps the life-breath in the eye; for without light, one cannot see.
The divinity that is in the earth supports a person’s out-breath, the Apana. What is between the sun and the earth is that which is Samana–the equalising breath. Air is the diffused breath, which is available for all creatures to breathe and be sustained. Fire, verily is the ascending-breath (Udana), therefore, he whose fire of life has ceased, goes through rebirth with his senses still clinging to the mind. Those who leave the body, for whom the aspiration for freedom is gone, they return to earth with the senses clinging to the mind.
Whatever is one’s thinking, there with one enters into the new life. His life (Prana) combined with fire (Udana) along with the Self leads to whatever world has been fashioned in thought.
The fire of desire catches on to that which you want to become and the Self leads you to whatever world has been fashioned by you in thought.