समान उ एवायं चासौ चोष्णोऽयमुष्णोऽसौ स्वर इतीममाचक्षते स्वर इति प्रत्यास्वर इत्यमुं तस्माद्वा एतमिमममुं चोद्गीथमुपासीत ॥ १.३.२ ॥
In plain words
This breath and that sun are alike: this one is warm, and that one is warm. This one men call sound, and that one they call reflected sound. Therefore let a man worship this one and that one as the Udgītha.
The commentators
Chāndogyopaniṣadbhāṣyam
यद्यपि स्थानभेदात्प्राणादित्यौ भिन्नाविव लक्ष्येते, तथापि न स तत्त्वभेदस्तयोः । कथम्—
समान उ एव तुल्य एव प्राण सवित्रा गुणत , सविता च प्राणेन , यस्मात् उष्णोऽय प्राण उष्णश्चासौ सविता । किंच स्वर इति इम प्राणमाचक्षते कथयन्ति, तथा स्वर इति प्रत्यास्वर इति च अमुं सवितारम् , यस्मात् प्राण स्वरत्येव न पुनर्मृत प्रत्यागच्छति, सविता तु अस्तमित्वा पुनरप्यहन्य हनि प्रत्यागच्छति, अत प्रत्यास्वर , अस्मात् गुणतो नाम- तश्च समानावितरेतर प्राणादित्यौ । अत तत्त्वाभेदात् एत प्राणम् इमम् अमुं च आदित्यम् उद्गीथमुपासीत ॥
In plain words
Although prana and the sun appear distinct because they occupy different places, there is no real difference between them. How is that?
Prāna and the sun are truly comparable in their attributes, for both are warm. Furthermore, people call this breath 'svara' and that sun 'pratyasvara' because breath moves forth without dying, while the sun sets and returns day after day. Thus, by virtue of both their qualities and their names, the breath and the sun are identical. Recognizing this unity of their essence, let one meditate upon both this breath and that sun as the Udgītha.
Close to the Sanskrit
Although due to difference of place prana and aditya appear as if distinct, nevertheless that is not the difference in reality of those two. How?
Equal indeed, comparable indeed is prana with the sun, by attribute, and the sun with prana, because this prana is hot and that sun is hot. Furthermore, this breath they call 'svara', and thus they call that sun 'pratyasvara', because prana sounds and does not return dead, whereas the sun having set returns day after day, hence 'pratyasvara'. From this quality and from name, prana and aditya are equal to each other. Therefore, due to the non-difference of their reality, one should meditate upon this prana and that sun as the Udgitha.