Mantra 2

तद्यत्तत्सत्यमसौ स आदित्यः ।य एष एतस्मिन्मण्डले पुरुषो यश्चायं दक्षिणेऽक्षन् पुरुषस्तावेतावन्योऽन्यस्मिन् प्रतिष्ठितौ ।रश्मिभिरेषोऽस्मिन् प्रतिष्ठितः प्राणैरयममुष्मिन् ।स यदोत्क्रमिष्यन् भवति शुद्धमेवैतन्मण्डलं पश्यति ।नैनमेते रश्मयः प्रत्यायन्ति ॥५,५.२ ॥

In plain words

And that real is the sun yonder. The person who is in that orb and the person who is in the right eye rest each upon the other: the one rests upon the other by its rays, and the other upon that one by the breaths. And when a man is about to depart, he sees that orb clear, and those rays no longer come to him.

The commentators

Bṛhadāraṇyakopaniṣadbhāṣyam· avatāraṇikā

अस्याधुना सत्यस्य ब्रह्मणः संस्थानविशेषे उपासनमुच्य- ते—

In plain words

Now he moves on to show how to meditate on this same Brahman, Truth, in one specific form it takes—

Close to the Sanskrit

Now, the meditation upon this Brahman, Truth, in a particular configuration, is declared—