अथ यदेतदादित्यस्य शुक्लं भाः सैवर्गथ यन्नीलं परः कृष्णं तत्साम तदेतदेतस्यामृच्यध्यूढं साम तस्मादृच्यध्यूढं साम गीयते ॥ १.६.५ ॥
atha yadetadādityasya śuklaṃ bhāḥ saivargatha yannīlaṃ paraḥ kṛṣṇaṃ tatsāma tadetadetasyāmṛcyadhyūḍhaṃ sāma tasmādṛcyadhyūḍhaṃ sāma gīyate || 1.6.5 ||
5. The white glow of the sun is the Ṛk, and its deep blue glow is the Sāma. The black glow called the Sāma is based on the white glow called the Ṛk. That is why the Sāma is sung based on the Ṛk.
Atha, next; yat etat, that which is this; ādityasya śuklam, whiteness of the sun; bhāḥ, the glow; sā eva ṛk, that is the Ṛk; atha, next; yat nīlam, that which is blue; paraḥ, deep; kṛṣṇam, black; tat sāma, that is the Sāma; tat etat sāma, this Sāma; etasyām ṛci adhyūḍham, is based on the Ṛk; tasmāt, that is why; ṛci adhyūḍham sāma gīyate, the Sāma is sung based on the Ṛk.
The Upaniṣad gives another way of worshipping the udgītha: The white glow of the sun is compared to the Ṛk. But the sun also has a deep blue or black glow, which the Upaniṣad compares to the Sāma. This deep blue glow is not seen by many, people. Only a few persons who have studied the scriptures and have acquired an enlightened mind can see it.