Bhashya
किंदेवतोऽस्यां ध्रुवायां दिश्यसीति ।मेरोः समन्ततो वसतामव्यभिचारात् ऊर्ध्वा दिक् ध्रुवेत्युच्यते ।अग्निदैवत इति— ऊर्ध्वायां हि प्रकाशभूयस्त्वम् , प्रकाशश्च अग्निः सोऽग्निः कस्मिन्प्रतिष्ठित इति, वाचीति ।कस्मिन्नु वाक्प्रतिष्ठितेति, हृदय इति ।तत्र याज्ञवल्क्यः सर्वासु दिक्षु विप्रसृतेन हृदयेन सर्वा दिश आत्मत्वेनाभि- संपन्नः ; सदेवाः सप्रतिष्ठा दिश आत्मभूतास्तस्य नाम- रूपकर्मात्मभूतस्य याज्ञवल्क्यस्य ; यत् रूपं तत् प्राच्या दिशा सह हृदयभूतं याज्ञवल्क्यस्य; यत्केवलं कर्म पुत्रो- त्पादनलक्षणं च ज्ञानसहितं च सह फलेन अधिष्ठात्रीभिश्च देवताभिः दक्षिणाप्रतीच्युदीच्यः कर्मफलात्मिकाः हृदयमेव आपन्नास्तस्य ; ध्रुवया दिशा सह नाम सर्वं वाग्द्वारेण हृदय- मेव आपन्नम् ; एतावद्धीदं सर्वम् ; यदुत रूपं वा कर्म वा नाम वेति तत्सर्वं हृदयमेव ; तत् सर्वात्मकं हृदयं पृच्छ्य- ते— कस्मिन्नु हृदयं प्रतिष्ठितमिति ॥
In plain words
What god watches over the direction that never moves? Call it 'fixed' because everything around Meru holds steady there without fail. Its god is Agni, because that's the direction thick with light, and light is Agni. What holds Agni up? Speech. What holds speech up? The heart. And here is the real turn: Yajnavalkya's heart has spread out through every direction until the directions themselves, gods and all, have become his own self. Whatever is form has folded, with the east, into his heart. Whatever is action — raising a child, knowing what you're doing, reaping the result, watched over by the south, the west, the north — has folded into his heart too. And whatever is name, riding in on speech from the fixed direction, has folded into his heart as well. That's the whole of it: form, action, name — take your pick, it's all just the heart. So now the only question left is the one that matters: what holds up the heart itself?
Close to the Sanskrit
'What deity do you have in this fixed direction?' — Because of the unfailing constancy of those who dwell all around Mount Meru, the direction above is called 'fixed'. 'Agni is the deity' — for in the upward direction there is an abundance of light, and light is Agni. That Agni — 'on what is he founded?' — 'On speech.' 'On what, then, is speech founded?' — 'On the heart.' Here, Yājñavalkya, by means of the heart spread out into all the directions, has become one with all the directions as his self; the directions, together with their deities and their supports, have become the self of Yājñavalkya, who has become identical with name, form and action. Whatever is form, that, together with the eastern direction, has become the heart-substance of Yājñavalkya. Whatever is mere action characterized by the begetting of a son, together with knowledge, together with its fruit, and together with the presiding deities — the southern, western and northern [directions], which are of the nature of action and its fruit — have themselves become the heart. Together with the fixed direction, the whole of 'name', by way of speech, has itself become the heart. This much indeed is all this universe; whatever there is, whether form, or action, or name, all of that is the heart alone. That heart, the self of everything, is asked about: on what, then, is the heart founded?