चक्षुरेवर्गात्मा साम तदेतदेतस्यामृच्यध्यूढंसाम तस्मादृच्यध्यूढंसाम गीयते । चक्षुरेव सात्मामस्तत्साम ॥ १.७.२ ॥
cakṣurevargātmā sāma tadetadetasyāmṛcyadhyūḍhaṃsāma tasmādṛcyadhyūḍhaṃsāma gīyate | cakṣureva sātmāmastatsāma || 1.7.2 ||
2. The eyes are like the Ṛg Veda, and the self [i.e., the form seen in the eyes] is like the Sāma, which is based on the Ṛk. This is why the Sāma is sung based on the Ṛk. The eyes are the sā, and the self [the form in the eyes] is the ama. The two together are Sāma.
Word-for-word explanation:
Cakṣuḥ eva ṛk, the eyes are like the Ṛg Veda; ātmā sāma, the self [as seen in the eyes] is the Sāma; tat etat sāma, this Sāma [called the ātmā]; etasyām ṛci adhyūḍham, is based on Ṛk [i.e., on the eyes]; tasmāt, this is why; ṛci adhyūḍham sāma gīyate, the Sāma is sung as based on the Ṛk; cakṣuḥ eva sā, the eyes are sā; ātmā amaḥ, the self [the form reflected in the eyes] is ama; tat sāma, that [if joined together] is Sāma.
Commentary:
The ātmā, or self, here means the form which is reflected in the eyes. This is why the Upaniṣad says the eyes are the Ṛg Veda„ and the self is the Sāma Veda.