Mahabharata 12.178.12
प्राणानां संनिपाताच्च संनिपातः प्रजायतेऊष्मा चाग्निरिति ज्ञेयो योऽन्नं पचति देहिनाम्
prāṇānāṃ saṃnipātācca saṃnipātaḥ prajāyateūṣmā cāgniriti jñeyo yo'nnaṃ pacati dehinām
Our plain-language meaning of this verse is waiting for scholar review.
Open in the book