Bhashya
पृथिव्येव यस्य देवस्य आयतनम् आश्रयः ; अग्निर्लोकोयस्य- लोकयत्यनेनेति लोकः, पश्यतीति- अग्निना पश्यती-त्यर्थः ; मनोज्योतिः- मनसा ज्योतिषा संकल्पविकल्पादि-कार्यं करोति यः, सोऽयं मनोज्योतिः ; पृथिवीशरीरःअग्निदर्शनः मनसा संकल्पयिता पृथिव्यभिमानी कार्यकर-णसंघातवान्देव इत्यर्थः ।य एवं विशिष्टं वै तं पुरुषं वि-द्यात् विजानीयात्, सर्वस्य आत्मनः आध्यात्मिकस्य का-र्यकरणसंघातस्य आत्मनः परमयनम् पर आश्रयः तंपरायणम्- मातृजेन त्वङ्मांसरुधिररूपेण क्षेत्रस्थानीयेनबीजस्थानीयस्य पितृजस्य अस्थिमज्जाशुक्ररूपस्य परम् अय-नम्, करणात्मनश्च—स वै वेदिता स्यात्; य एतदेवं वेत्तिस वै वेदिता पण्डितः स्यादित्यभिप्रायः ।याज्ञवल्क्य त्वंतमजानन्नेव पण्डिताभिमानीत्यभिप्रायः ।यदि तद्विज्ञानेपाण्डित्यं लभ्यते, वेद वै अहं तं पुरुषम्-सर्वस्य आत्मनःपरायणं यमात्थ यं कथयसि- तमहं वेद ।तत्र शाकल्य-स्य वचनं द्रष्टव्यम्-यदि त्वं वेत्थ तं पुरुषम्, ब्रूहि किंवि-शेषणोऽसौ ।शृणु, यद्विशेषणः सः— य एवायं शारीरः-पार्थिवांशे शरीरे भवः शारीरः मातृजकोशत्रयरूप इत्य-र्थः; स एष देवः, यस्त्वया पृष्टः, हे शाकल्य; किंतुअस्ति तत्र वक्तव्यं विशेषणान्तरम्; तत् वदैव पृच्छेवेत्यर्थः,हे शाकल्य ।स एवं प्रक्षोभितोऽमर्षवशग आह, तोत्रार्दितइव गजः— तस्य देवस्य शारीरस्य का देवता- यस्मा-न्निष्पद्यते, यः ‘सा तस्य देवता’ इत्यस्मिन्प्रकरणे विव-क्षितः; अमृतमिति होवाच- अमृतमिति यो भुक्तस्यान्नस्यरसः मातृजस्य लोहितस्य निष्पत्तिहेतुः; तस्माद्धि अन्नर-साल्लोहितं निष्पद्यते स्त्रियां श्रितम्; ततश्च लोहितमयं श-रीरं बीजाश्रयम् ।समानमन्यत् ॥
In plain words
‘Earth is the abode’ — meaning, this deity's support. ‘Fire is the world’ — a world is called loka because you see by it; put plainly, you see by means of fire. ‘Mind is the light’ — the one who does the work of resolving, doubting, and the rest, by mind as light, that one is this mind-as-light. Earth for a body, fire for sight, mind for resolve, identified with the earth, carrying the whole bundle of body and organs — that is what 'deity' means here. Whoever comes to know a person marked out this way as the highest resting place of every self — of the self bound up in this body and its instruments — as the final home even of the instrumental self built from the father's contribution, bone, marrow, seed, resting on the mother's contribution, skin, flesh, blood, which serves as its field — that person truly knows. Whoever knows this, truly knows, is truly learned — that's the point being made. The hidden jab is this: Yājñavalkya, you don't actually know this person, you only think you're learned. So Yājñavalkya answers: if learning comes from knowing that, then yes — I do know that person, the final refuge of every self, the one you're asking about. I know him. Now watch what Śākalya says next: if you really know him, tell me — what further mark identifies him? Listen, he says, here is his mark: this very embodied one — living in the earthy part of the body, made of the three sheaths that come from the mother — that is this deity, Śākalya, the very one you asked about. But there's still another mark to be given; go on, ask for it — that's the sense of it. And at that, Śākalya, stung, bristling with irritation, cries out like an elephant jabbed with the goad: what deity stands behind that bodily deity, the one it springs from — the deity meant by the standing refrain, 'that is his deity'? ‘The immortal,’ Yājñavalkya says. And 'immortal' means the sap of food once it's been eaten, the very thing that becomes the mother's blood; for it is from that sap of food that blood arises and settles in the woman, and from that blood-formed substance a body takes shape, one built to house the seed. The rest follows exactly the same pattern.
Close to the Sanskrit
'Earth is the abode' — the support of that deity. 'Fire is the world' — of that [deity]: a world (loka) is so called because 'one perceives by means of it' — that is, 'one perceives by means of fire' is the meaning. 'Mind is the light' — by mind, as light, he who performs the function of resolve, doubt, and so on, he is this mind-as-light. Earth-bodied, fire-seeing, one who resolves by mind, identified with earth, possessing the aggregate of effect and cause — that is the meaning of 'deity'. Whoever should know, should understand, that person thus qualified as the highest resort, the supreme refuge, of the self of all — of the self of the individual's aggregate of effect and cause — as the final resting-place also of the instrumental self, made from the paternal element in the form of bone, marrow, and semen, whose site is the seed, [resting] on the maternal element in the form of skin, flesh and blood which functions as the field — he indeed would be a knower. Whoever knows this thus, he indeed would be a knower, a learned man — such is the implication. [Implied:] Yājñavalkya, you, without even knowing that person, have the conceit of being learned. [Yājñavalkya replies:] If learnedness is gained through knowledge of that, then indeed I know that person, the final refuge of the self of all, of whom you speak — that one I know. There, Śākalya's statement is to be noted: if you know that person, tell — by what further attribute is he characterized? Listen, this is his attribute: this one indeed, the bodily one — existing in the body, in the earthy portion, in the form of the three maternal sheaths — that is the meaning; that is this deity you asked about, O Śākalya. But there remains another attribute still to be stated; [Yājñavalkya says] tell it, go on and ask — that is the meaning, O Śākalya. He, thus provoked, overcome by indignation, spoke, like an elephant struck by the goad: what is the deity of that bodily deity, from which it arises — which is intended, in this context, by the refrain 'that is his deity'? 'The immortal,' he said. 'Immortal' [means] the sap of the food that has been eaten, the cause of the production of the blood derived from the mother; for indeed, from the sap of food, blood is produced, which resides in the woman; and from that, the blood-formed body, the receptacle of the seed [is formed]. The rest is the same.