The Chandogya Upanishad talks of five deities, Aditya, Chandra, Agni, Parjanya and Akasa, as the door keepers of the world of Brahman. The Upanishad then goes on to talk of meditation of Brahman as gastric fire. The Upanishad says that the light of this fire is the same as the light that shines above the highest worlds, explained M.K. Srinivasan in a discourse.
The gastric fire is said to be ‘antarjyotih.’ That means that this gastric fire is the body of the Supreme Brahman.
The word ‘antarjyotih’ is also used by Vedanta Desika in his Bhagavad Dhyana Sopana, where he describes Lord Ranganatha of Srirangam. Desika says the Lord is daivatam daivatAnAm — the God of all gods, the only One who can grant moksha.
In the Bhagavad Gita, the Supreme One is said to be of the form of VaisvAnara agni.
Chandogya Upanishad also talks of how this gastric fire can be perceived. It can be felt by experiencing the heat of the body, which is felt by touch. It can also be perceived as the internal sound one hears when the ears are closed, the rumbling in the ears. This rumbling is the sound of that Agni. So this Jyoti is drishtatva and srutatva — that is, it should be meditated upon as seen and heard.
The Supreme One is known through meditation. This Paramatman, who has all auspicious qualities, resides in the heart.
He is smaller than the smallest grain of rice; smaller than a mustard seed. Yet He is greater than all the worlds. He assumes a small proportion in order to reside in our hearts, and this is to facilitate our meditation on Him. He who believes firmly that he will reach Sri Vaikuntha when he departs from this world shall definitely reach the abode of the Supreme One.
