अरा इव रथनाभौ संहता यत्र नाड्यः स एषोऽन्तश्चरते बहुधा जायमानः ।ओमित्येवं ध्यायथ आत्मानं स्वस्ति वः पाराय तमसः परस्तात् ॥ ६ ॥
In plain words
Where the Nāḍīs are joined like spokes at the nave of a wheel, this Ātma moves within, becoming manifold. Meditate on Ātma thus as Oṃ. Blessings to you for crossing beyond the darkness, to the farther shore.
The commentators
Muṇḍakopaniṣadbhāṣyam· bhāṣya
किंच, अरा इव यथा रथनाभौ समर्पिता अरा , एव संहता संप्रविष्टा यत्र यस्मिन्हृदये सर्वतो देहव्यापिन्य नाड्य , तस्मिन्हृदये बुद्धिप्रत्ययसाक्षिभूत स एष प्रकृत आत्मा अन्त मध्ये चरते चरति वर्तते । पश्यन् शृण्वन्मन्वानो विजानन् बहुधा अनेकधा क्रोधहर्षादिप्रत्ययैर्जायमान इव जायमान अन्त करणोपाध्यनुविधायित्वात् , वदन्ति हि लौकिका हृष्टो जात क्रुद्धो जात इति । तमात्मानम् ओमित्येवम् ओंकारालम्बना सन्त यथोक्तकल्पनया ध्यायथ चिन्तयत । उक्त च वक्तव्य शिष्येभ्य आचार्येण जानता । शिष्याश्च ब्रह्मविद्याविविदिषुत्वान्निवृत्तकर्माणो मोक्षपथे प्रवृत्ता । तेषां निर्विघ्नतया ब्रह्मप्राप्तिमाशास्त्याचार्य — स्वस्ति निर्विघ्नमस्तु व युष्माकं पाराय परकूलाय , कस्य ? अविद्यातमस परस्तात् , अविद्यारहितब्रह्मस्वरूपगमनायेत्यर्थ ॥
In plain words
The Nāḍīs, the channels that run throughout the body, converge in the heart just as the spokes of a wheel meet in its hub. There abides Ātman, the witness of every cognition in Buddhi. Ātman seems to see, hear, think, and know, and seems to be born into each new state of anger, delight, and the rest, because it follows the changing Upādhi of the Antaḥkaraṇa. This is why people say, “He became joyful” or “He became angry.” Let Oṃkāra be the support, and meditate on that Ātman as Oṃ in the manner already taught. The knowing Ācārya gives this teaching to disciples who long for Brahmavidyā, have turned away from karma, and have entered the path of mokṣa. He blesses their journey to Brahman: “May your crossing to the farther shore be free of every obstacle.” That shore lies beyond the darkness of avidyā; it is Brahma-Svarūpa, the nature of Brahman in which avidyā is absent.
Close to the Sanskrit
Further, just as spokes are set in the hub of a chariot wheel, so the Nāḍīs that pervade the body from every side are gathered and enter the heart. Within that heart moves—abides—this Ātman under discussion, the witness of the cognitions of Buddhi. Seeing, hearing, thinking, and knowing, it appears to be born in many ways through cognitions such as anger and joy because it conforms to the Upādhi of the Antaḥkaraṇa. Thus ordinary people say, “He has become joyful; he has become angry.” Meditate upon that Ātman as Oṃ, resting on Oṃkāra and following the method already stated. This has been said, and is to be taught to the disciples by the Ācārya who knows. The disciples, wishing to know Brahmavidyā, have withdrawn from karma and entered the path of mokṣa. The Ācārya wishes them an unobstructed attainment of Brahman: “May there be well-being—freedom from obstacles—for your crossing to the farther bank.” The farther bank of what? Beyond the darkness of avidyā. The meaning is: for reaching Brahma-Svarūpa, the nature of Brahman free from avidyā.