Verse 6.16.3

स यथा तत्र नादाह्येतैतदात्म्यमिदं सर्वं तत्सत्यं स आत्मा तत्त्वमसि श्वेतकेतो इति तद्धास्य विजज्ञाविति विजज्ञाविति ॥ ६.१६.३ ॥
॥ इति षोडशः खण्डः ॥
॥ इति षष्ठोऽध्यायः ॥

sa yathā tatra nādāhyetaitadātmyamidaṃ sarvaṃ tatsatyaṃ sa ātmā tattvamasi śvetaketo iti taddhāsya vijajñāviti vijajñāviti || 6.16.3 ||
|| iti ṣoḍaśaḥ khaṇḍaḥ ||
|| iti ṣaṣṭho'dhyāyaḥ ||

3. ‘That man, being honest, is not affected by the hot axe. That [Self] is the Self of all this. It is the Truth. It is the Self. That thou art, O Śvetaketu.’ Śvetaketu learnt this well from his father.

Word-for-word explanation:

Yathā, as; saḥ, he; tatra, in such circumstances; na adāhyet, is not burned; idam sarvarn aitadātmyam, the Self of all this; tat satyam, that is the Truth; saḥ ātmā, that is the Self; tat, that; tvam, you; asi, are; śvetaketo iti, O Śvetaketu; asya, from him [his father]; tat ha, that [Self]; vijajñau iti, he clearly learnt; vijajñau iti, he clearly leamt. Iti ṣoḍaśaḥ khaṇḍaḥ, here ends the sixteenth section. Iti chāndogyopaniṣadi ṣaṣṭhaḥ adhyāyaḥ, here ends the sixth chapter of the Chāndogya Upaniṣad.

Commentary:

“Idam sarvam”—all this. ‘This’ refers to this phenomenal world which we see, with which we are familiar. Please remember, even in this unreal phenomenal world that one unchangeable essence exists. Tat satyam—that is the Reality. Sri Ramakrishna used to give the example of pillows. Pillows may be different sizes, different shapes, and have different functions, but inside all of them is the same silk-cotton, the same essence. Similarly, within this phenomenal world there is one essence, one Reality. And that is our Self. Tat tvam asi—you are that.

This chapter stresses the idea that there is something—we call it pure Spirit—from which everything has emerged, on which everything rests, and into which everything finally merges. There is something common from which we have all come, on which we all rest, and into which we all go back. That something is always constant.

Think of the ocean, for example. Where do the waves come from? The ocean. What supports them? The ocean. Where do they finally go? Back to the ocean. This coming and going, back and forth—we see this happening all the time, with everything. We are born, we remain for a while, and then we die. Over and over again—we come from Brahman, we are sustained by Brahman, and we go back to Brahman. But all the time we are that Brahman. As the waves are nothing but the ocean, similarly, we are nothing but Brahman.

Sri Ramakrishna used to say that the relative and the Absolute are the same. The Absolute is compared to a snake coiled up, sleeping on the ground, and the relative is like a snake in motion, raising its hood.

But when everything disappears, when there is no phenomenal world, what remains? We do not know. There is a vast, infinite One. We cannot describe it, because it has no name and no form. How can you describe something that is nameless and formless?

Suppose you say ‘white.’ Can you understand ‘white’ without a white object? There must be a particularization. A white flower, or a white shirt, we can understand. Similarly, how can we understand pure Existence? This is why the Upaniṣad simply calls it tat, that.

Vedānta says that the One has become many, but this many does not make a real modification or change in the One. The One remains One. It only appears to be many.