The concept of Agni is basic concept of Ayurveda. This Siddhanta provides fundamental knowledge for understanding of the theories
of Ayurveda viz. Ahara Pacana, Dhatu Utpatti, Vyadhi Utpatti, Ayu Parijnana etc.
Agni is believed to be the agency for any kind of transformation. It is a known fact that at each and every second multiple procedures
of transformations take place in the body. These may be bio chemical or bio physical or any other type of bio transformations. Due to
these constant transformation procedures, body grows, develops and lastly destroys too. Thinking on this line; it can be said that life is
nothing but a constant process of transformations. Diseased state of the body is also some pathological changes either functional or
structural. Thus the principle of Agni becomes vital as either the healthy or the diseased state can only be understood with
understanding of changes.
Jatharagni situated below the Amasaya in Garahani is activated by Samana Vayu and digests the food which is taken in proper Matra
and in proper manner observing all the Aharavidhivisesayatanas and Ahara Vidhividhana, in order to increase the longevity of life.
All this process can be compared with that of the preparation of rice for meals in a vessel kept on a stove with fire under the vessel.
Ayurvedic concept of Jatharagni is best explained in the terms of Pittosma, unlike the Usma form of Agni in the animate world,
because Pitta is a speciality of the living body. In Astanga Samgraha Vrddha Vagbhata quotes that according to a group of Acaryas;
Agni is nothing but combined heat of Dosa, Dhatu and Malas.