Verse 8.12.6

तं वा एतं देवा आत्मानमुपासते तस्मात्तेषां सर्वे च लोका आत्ताः सर्वे च कामाः स सर्वांश्च लोकानाप्नोति सर्वांश्च कामान्यस्तमात्मानमनुविद्य विजानातीति ह प्र्जापतिरुवाच प्रजापतिरुवाच ॥ ८.१२.६ ॥
॥ इति द्वादशः खण्डः ॥

taṃ vā etaṃ devā ātmānamupāsate tasmātteṣāṃ sarve ca lokā āttāḥ sarve ca kāmāḥ sa sarvāṃśca lokānāpnoti sarvāṃśca kāmānyastamātmānamanuvidya vijānātīti ha prjāpatiruvāca prajāpatiruvāca || 8.12.6 ||
|| iti dvādaśaḥ khaṇḍaḥ ||

6. This Self is worshipped by the gods. This is why all worlds and all desirable things are within their grasp. One who fully understands and realizes this Self [with the help of teachers and the scriptures] is able to attain whatever worlds and whatever desirable things he wants. This is what Prajāpati taught Indra.

Word-for-word explanation:

Tam vai etam devāḥ ātmānam upāsate, that is the Self which the gods worship; tasmāt, this is why; sarve ca lokāḥ, all the worlds; teṣām āttāḥ, are within the grasp of them [the gods]; sarve ca kāmāḥ, and all things they desire; sarvān ca lokān, all worlds; sarvān ca kāmān, and all things one desires; āpnoti, one attains; yaḥ tam ātmānam anuvidya, one who knows the Self; vijānāti iti, and has a direct, personal experience of it; prajāpatiḥ ha uvāca prajāpatiḥ uvāca, this is what Prajāpati taught. Iti dvādaśaḥ khaṇḍaḥ, here ends the twelfth section.

Commentary:

Here the Upaniṣad is praising Self-knowledge in order to tempt us to attain it. Earlier the Upaniṣad said, ‘Na alpe sukḥam asti’—there is no happiness in the finite, in what is small or limited. Only in bhūmā, the infinite, is there happiness. Bhūmā is infinite in terms of both time and space. Whatever is limited by time and space cannot give us peace and happiness.

Even the state of a god or goddess is a limitation, according to Hinduism. By virtue of the kind of life you have lived and the good things you have done, you may be elevated to the position of a god or goddess. But that position is only temporary. When your term expires, you are right back where you

Śaṅkara says the Upaniṣad does not mean to say that this state can be attained only by gods and goddesses. It is for human beings also. In fact, it is our very birthright.

The story of Indra and Virocana going to Prajāpati for Self-knowledge shows that we are all suffering from discontent. We are always seeking something, though we may not know exactly what it is. Even the gods and goddesses in heaven are not content. After many births they have attained the status of a god or goddess, and they seem to have everything they desire, yet still they are not satisfied.

This is why Indra went to Prajāpati and spent a hundred and one years practising austerities to get the knowledge of the Self. The Upaniṣad says again and again that Self-knowledge is the highest. If you attain that you attain everything.