Bhashya
न उक्तोत्तरत्वात् ।प्रमाणस्य हि प्रमाणत्वम् अप्रमाणत्वं वा प्रमोत्पादनानुत्पादननिमित्तम्, अन्यथा चेत् स्तम्भादीनां प्रामाण्यप्रसङ्गात् शब्दादौ प्रमेये ।किंचातः ? यदि तावत् उपनिषदो ब्रह्मैकत्वप्रतिपत्तिप्रमां कुर्वन्ति, कथमप्रमाणं भवेयुः ।न कुर्वन्त्येवेति चेत्- यथा अग्निः शीतम्- इति, स भवानेवं वदन् वक्तव्यः- उपनिषत्प्रामाण्यप्रतिषेधार्थं भवतो वाक्यम् उपनिषत्प्रामाण्यप्रतिषेधं किं न करोत्येव, अग्निर्वा रूपप्रकाशम् ; अथ करोति- यदि करोति, भवतु तदा प्रतिषेधार्थं प्रमाणं भवद्वाक्यम्, अग्निश्च रूपप्रकाशको भवेत् ; प्रतिषेधवाक्यप्रामाण्ये भवत्येवोपनिषदां प्रामाण्यम् ।अत्रभवन्तो ब्रुवन्तु कः परिहार इति ।ननु अत्र प्रत्यक्षा मद्वाक्य उपनिषत्प्रामाण्यप्रतिषेधार्थप्रतिपत्तिः अग्नौ च रूपप्रकाशनप्रतिपत्तिः प्रमा ; कस्तर्हि भवतः प्रद्वेषः ब्रह्मैकत्वप्रत्यये प्रमां प्रत्यक्षं कुर्वतीषु उपनिषत्सु उपलभ्यमानासु ? प्रतिषेधानुपपत्तेः ।शोकमोहादिनिवृत्तिश्च प्रत्यक्षं फलं ब्रह्मैकत्वप्रतिपत्तिपारम्पर्यजनितम् इत्यवोचाम ।तस्मादुक्तोत्तरत्वात् उपनिषदं प्रति अप्रमाण्यशङ्का तावन्नास्ति ॥
In plain words
No — we've already answered this. Whether any means of knowledge is valid or not comes down to one thing alone: does it produce correct knowledge, or doesn't it? If that weren't the test, then even a bare post could count as a valid authority on the meaning of words. So where does that leave us? If the Upanishads do produce correct knowledge that Brahman is one, how could they possibly be invalid? Say you insist they produce no such thing — that's exactly like insisting fire is cold. Here's the answer you're owed: does your own statement, whose entire purpose is to deny the Upanishads' authority, actually manage to deny it — the way fire manages to give off light? Or doesn't it? If it does succeed, then your statement is a valid instrument for that denial, and by the same measure fire is a valid producer of light — fine. But grant your denial-statement its validity, and the Upanishads' validity comes along with it, by the very same logic. So let our opponents tell us: what is the way out of this? 'But surely,' they say, 'my own understanding that I'm denying the Upanishads, and the way I directly perceive light coming from fire, are both simply valid knowledge.' Then what exactly do you have against the Upanishads, which we watch producing valid knowledge of Brahman's oneness right in front of us? There's no way to deny them that makes sense. And the visible fruit of that knowledge — the falling away of grief and confusion — follows directly from realizing that Brahman is one, as we've already shown. So because this has already been settled, there is, in the end, no real doubt left about whether the Upanishads can be trusted.
Close to the Sanskrit
No, because this has already been answered. For the validity or invalidity of a means of knowledge has as its cause the production or non-production of valid cognition; otherwise, there would follow the undesired consequence that a pillar and the like are valid means of knowledge regarding an object such as word. So what then? If, to begin with, the Upanishads produce valid cognition of the realization of Brahman's oneness, how could they be invalid? If [you say]: 'They do not produce it at all' — that would be like saying 'fire is cold.' You, sir, speaking thus, must be answered: does your statement, whose purpose is to deny the validity of the Upanishads, fail to produce that very denial — the way fire fails to produce the manifestation of form? Or does it succeed? If it succeeds, then let your statement be a valid means of knowledge for the purpose of denial, and let fire too be a producer of the manifestation of form; [but] once the denying statement's validity is granted, the validity of the Upanishads certainly follows as well. Let the venerable opponents state what way out there is. But surely, [you say,] here the cognition of the purport of my statement denying the Upanishads' validity, and likewise the cognition of the manifestation of form in fire, are both directly evident valid cognitions; what, then, is your hostility toward the Upanishads, which are directly seen producing valid cognition regarding the notion of Brahman's oneness? — Because denying them makes no sense. And the cessation of grief, delusion, and the like is the directly observed result born, in due sequence, from realizing the oneness of Brahman — as we have already said. Therefore, because this has already been answered, there is, to that extent, no doubt at all about the Upanishads' invalidity.