The Flame in the Heart
The Vedas not only equate the Self with fire, they also equate the heart, which is the seat of the Self, with fire. The Self is said to exist like a flame the size of a thumb in the heart. This small flame in the heart is the real person, power and presence that allows the body and mind to function. It is like the pilot light in a stove that lights all the other burners on the stove. The light of the Self lights all the other fires of the body, prana, senses and mind. Even the digestive fire can only work with its support.
This flame of the Self sustains us through all our states of waking, dream and deep sleep and through the entire process of birth or death. Even prana or the life-force is but its manifestation or shadow. This flame leaves the body at death and carries the samskaras that propel us on to another birth. Only for those who are fully Self-realized, who have totally merged into their inner fire, are able to escape this process.
The great fire (Mahan Agni) in the heart is the subtle body (or linga) and the being behind it of lightning-like appearance is the individual soul or Jivatman. At its core is the atomic point of the Supreme Self which is the doorway into the infinite light, the Sun of suns, the God of Gods. Indeed we could say that the hridaya or heart that Ramana emphasizes is also this flame that dwells there. The heart, Agni and Atman are ultimately three ways of looking at the same supreme truth.
Cultivating Inner Fire
Self-inquiry is a lot like cultivating a fire. Our awareness grows by offering our speech, breath and mind into the witnessing Self that is the eternal and inextinguishable flame within us. It is the quality and consistency of our offering that is the main factor in growing this flame, not any outer formulas or formalities. We must maintain our awareness like a fire, keeping it from going out even for an instant by continually offering our mental modifications into it as its fuel.
Indeed we could say that the modifications of the mind are nothing but the smoke coming forth from an improperly burning fire of awareness. When that inner flame burns cleans and consistently then there is only pure light and the mind itself gets merged in its source.
For Self-inquiry to be a living process we must invoke and incarnate that inner flame of knowing in our daily lives. Self-inquiry is not a matter of ordinary thinking or logic. It is not a matter of emotion or feeling either. It is not a matter of just blanking or stopping the mind as it is. Nor is it some esoteric intuition. It is the most fundamental form of knowledge, perception or consciousness that we have. It is cultivating the pure light behind all the glitter and shadow of the mind and senses. The Self is the mind behind the mind, the eye behind the eye, the speech behind speech and the prana behind prana as the Upanishads so eloquently state.
Behind all of our senses through which we perceive the external world is a more primary internal sense of self-being through which we know that we exist and through which we are one with all existence. This self-sense is more immediate than all the outer senses which are only possible through it. But it is so immediate and given, our very sense of being, that we take it for granted and ignore it. In the maze of sensory information we lose track of who we really are. We get caught in the movements of the body and the mind and forget our true nature that transcends them and for which alone they work.
We must remember this very subtle inner fire through which the mind and senses shine and reveal their objects of perception. Cultivating this direct awareness of the Self (aparoksha anubhava of Vedanta) is a lot like conducting a fire sacrifice. Behind all of our states of mind, even the most ignorant or confused, like a flame hidden in darkness, the Self shines as the eternal witness of all. What is important is to bring that flame out, like a fire hidden in wood, through the friction of inquiry.
This Self within the heart transcends all the worlds. As the supreme Agni or digestive power, it has the capacity to eat or absorb the entire universe.