Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 40

Sanskrit:

द्योतनं पचनं पानमदनं हिममर्दनम् ।तेजसो वृत्तयस्त्वेता: शोषणं क्षुत्तृडेव च ॥ ४० ॥

ITRANS:

dyotanaṁ pacanaṁ pānamadanaṁ hima-mardanamtejaso vṛttayas tv etāḥśoṣaṇaṁ kṣut tṛḍ eva ca

Translation:

Fire is appreciated by its light and by its ability to cook, to digest, to destroy cold, to evaporate, and to give rise to hunger, thirst, eating and drinking.

Purport:

The first symptoms of fire are distribution of light and heat, and the existence of fire is also perceived in the stomach. Without fire we cannot digest what we eat. Without digestion there is no hunger and thirst or power to eat and drink. When there is insufficient hunger and thirst, it is understood that there is a shortage of fire within the stomach, and the Āyurvedic treatment is performed in connection with the fire element, agni-māndyam. Since fire is increased by the secretion of bile, the treatment is to increase bile secretion. The Āyurvedic treatment thus corroborates the statements in Śrīmad-Bhāgavatam. The characteristic of fire in subduing the influence of cold is known to everyone. Severe cold can always be counteracted by fire.