Rooted in the stories of the Rig Veda (an ancient Sanskrit text) the story of Agni refers to a god or high priest. In Yogic theory, Agni represents our spiritual fire.
Through our practice we create Tapas which means to burn or cook. Tapas occurs through the use of Agni. Through Tapas we are able to create Kriya or cleansing. Our Asana practice is the most tangible way to experience the heating of Agni. As our body moves, the heat grows, as the heat grows we begin to "cook" through Tapas and eliminate what we no longer need through sweating (Kriya). However, the practices of Pranayama as well as the rest of the 8 limbs can do the same but in different ways.
By practicing the Yamas and the Niyamas we remove our habits of lying and hurtful actions. Through concentration we are able to still the mind and remove cita (mind chatter). Through meditation we still the body and mind; eliminating the distractions that lie outside of our Self. Finally, in Samadhi (bliss) we are free from all impurities.
Our goal is to allow Agni to burn to help remove impurities and discover our true Self which lies hidden beneath the layers that distract us.