Bhashya
के पुनस्तस्य चमसस्य तीरे आसत ऋषय इति- इमावेव गोतमभरद्वाजौ कर्णौ- अयमेव गोतमः अयं भरद्वाजः दक्षिणश्च उत्तरश्च, विपर्ययेण वा ।तथा चक्षुषीउपदिशन्नुवाच— इमावेव विश्वामित्रजमदग्नी दक्षिणं वि-श्वामित्रः उत्तरं जमदग्निः, विपर्ययेण वा ।इमावेव वसि-ष्ठकश्यपौ— नासिके उपदिशन्नुवाच ; दक्षिणः पुटो भवतिवसिष्ठः ; उत्तरः कश्यपः—पूर्ववत् ।वागेव अत्रिः अदनाक्रि-यायोगात् सप्तमः ; वाचा ह्यन्नमद्यते ; तस्मादत्तिर्ह वै प्रसिद्धंनामैतत्— अत्तृत्वादत्तिरिति, अत्तिरेव सन् यदत्रिरित्युच्यतेपरोक्षेण ।सर्वस्य एतस्यान्नजातस्य प्राणस्य, अत्रिनिर्वचन-विज्ञानादत्ता भवति ।अत्तैव भवति नामुष्मिन्नन्येन पुनः प्र-त्यद्यते इत्येतदुक्तं भवति— सर्वमस्यान्नं भवतीति ।य एवम्एतत् यथोक्तं प्राणयाथात्म्यं वेद, स एवं मध्यमः प्राणो भूत्वाआधानप्रत्याधानगतो भोक्तैव भवति, न भोज्यम् ; भोज्या-द्व्यावर्तत इत्यर्थः ॥
In plain words
So who exactly were the seers sitting on the rim of that cup? Gotama and Bharadvāja are the two ears — one is Gotama, the other Bharadvāja, right and left, or the reverse; it doesn't matter which. Pointing to the eyes next, he said: Viśvāmitra and Jamadagni — the right eye is Viśvāmitra, the left is Jamadagni, or again the reverse. Vasiṣṭha and Kaśyapa, pointing to the nostrils: the right flap is Vasiṣṭha, the left is Kaśyapa, same as before. And Speech alone is Atri, the seventh, because speech is bound up with the very act of eating — food gets eaten by speech. That's why 'eating' is this thing's open, well-known name: he's called 'atti' because he's an eater, an attṛ, and being exactly that eater, he carries the veiled name 'Atri.' By understanding what that name secretly means, he becomes the eater of this whole mass of food the breath is made of. He becomes the eater, full stop — never again eaten by anyone else out there. That's what 'everything becomes his food' really says. And whoever knows the breath's true nature this way becomes, as the middle breath, someone who only eats and is never eaten, no matter how he is placed or displaced. He steps free of ever being food himself — that is the point.
Close to the Sanskrit
Who, again, were the seers that sat on the rim of that cup? — These two indeed, Gotama and Bharadvāja, are the two ears; this one indeed is Gotama, this is Bharadvāja — the right and the left respectively, or conversely. Likewise, pointing to the two eyes, he said — these two indeed, Viśvāmitra and Jamadagni; the right is Viśvāmitra, the left is Jamadagni, or conversely. These two indeed, Vasiṣṭha and Kaśyapa — pointing to the two nostrils, he said; the right flap is Vasiṣṭha, the left is Kaśyapa — as before. Speech alone is Atri, the seventh, on account of its connection with the act of eating; for food is eaten by speech; therefore 'eating' indeed is this well-known name — because he is an eater, 'atti'; being precisely the eater, he is called 'Atri' by an indirect transformation of the word. Of this entire mass of food that is the breath, he becomes the eater through understanding the etymological meaning of 'Atri.' He becomes the eater alone, and is not, in turn, eaten again by another there — that is what is meant by 'everything becomes his food.' Whoever thus knows this true nature of the breath as described, he, having become in this way the middle breath, caught up in the cycle of placement and re-placement, becomes only the eater, not the eaten; he is excluded from being food — that is the meaning.