Bhashya
तद्वा एतदक्षरं गार्गि अदृष्टम्, न केनचिद्दृष्टम्, अवि-षयत्वात् स्वयं तु द्रष्टृ दृष्टिखरूपत्वात् ।तथा अश्रुतं श्रोत्रा-विषयत्वात्, स्वयं श्रोतृ श्रुतिस्वरूपत्वात् ।तथा अमतं मनसो-ऽविषयत्वात्, स्वयं मन्तृ मतिस्वरूपत्वात् ।तथा अविज्ञातंबुद्धेरविषयत्वात्, स्वयं विज्ञातृ विज्ञानस्वरूपत्वात् ।किं चनान्यत् अतः अस्मादक्षरात् अस्ति- नास्ति किंचिद्द्रष्टृदर्शनक्रियाकर्तृ; एतदेवाक्षरं दर्शनक्रियाकर्तृ सर्वत्र ।तथानान्यदतोऽस्ति श्रोतृ; तदेवाक्षरं श्रोतृ सर्वत्र ।नान्यदतो-स्ति मन्तृ; तदेवाक्षरं मन्तृ सर्वत्र सर्वमनोद्वारेण ।नान्यद-तोऽस्मि विज्ञातृ विज्ञानक्रियाकर्तृ, तदेवाक्षरं सर्वबुद्धिद्वारेणविज्ञानक्रियाकर्तृ, नाचेतनं प्रधानम् अन्यद्वा ।एतस्मिन्नुखल्वक्षरे गार्ग्याकाश ओतश्च प्रोतश्चेति ।यदेव साक्षादप-रोक्षाद्ब्रह्म, य आत्मा सर्वान्तरः अशनायादिसंसारधर्मातीतः, यस्मिन्नाकाश ओतश्च प्रोतश्च- एषा परा काष्ठा, एषा परा गतिः, एतत्परं ब्रह्म, एतत्पृथिव्यादेराकाशान्तस्य सत्यस्य सत्यम् ॥
In plain words
This, Gārgī, is the Imperishable. No one has ever seen it, because it is never an object for the eyes — yet it is itself the seer, since seeing is exactly what it is. In the same way, no one has heard it, yet it is the hearer; no one has thought it, yet it is the thinker; no one has known it as a thing, yet it is the knower. And nothing else is at work here at all: whenever anything sees, this alone is doing the seeing; whenever anything hears, this alone is doing the hearing; whenever anything thinks, this alone is thinking, working through every mind there is; whenever anything knows, this alone is knowing, working through every intellect there is. It isn't blind, unconscious matter, and it isn't anything else you could name. And in this very Imperishable, Gārgī, space itself is woven, through and through. This — the reality that is brahman, known directly, nothing standing between; the innermost Self, beyond hunger, beyond every condition of the wandering, suffering life — this, in which space is woven crosswise and lengthwise, is the furthest goal there is. It is the highest path. It is brahman itself, supreme. It is the Truth behind the truth of everything from the earth beneath your feet to the sky above your head.
Close to the Sanskrit
This, verily, Gārgī, is that Imperishable: unseen, not seen by anyone, because it is not an object of sight; but itself the seer, because its very nature is seeing. Likewise unheard, because it is not an object even for the ear; itself the hearer, because its nature is hearing. Likewise unthought, because it is not an object for the mind; itself the thinker, because its nature is thought. Likewise unknown, because it is not an object for the intellect; itself the knower, because its nature is knowledge. Moreover, there is nothing else besides this Imperishable: there is no other seer, no other agent of the act of seeing; this very Imperishable is the agent of seeing everywhere. Likewise there is no other hearer besides this; this very Imperishable is the hearer everywhere. There is no other thinker besides this; this very Imperishable is the thinker everywhere, through every mind. There is no other knower, no other agent of the act of knowing, besides this; this very Imperishable, through every intellect, is the agent of knowing — not unconscious matter, nor anything else. In this Imperishable, indeed, Gārgī, ether is woven, crosswise and lengthwise. That very reality which is brahman, known directly and without mediation, which is the Self, the innermost of all, beyond hunger and the rest and beyond all conditions of transmigratory existence — in which ether is woven, crosswise and lengthwise — this is the highest goal, this is the highest path, this is the supreme brahman, this is the Truth of the truth that reaches from earth to ether.