अथ यत्सगववेलाया ँ स आदिस्तदस्य वया ँ स्यन्वायत्तानि तस्मात्तान्य-न्तरिक्षेऽनारम्बणान्यादायात्मानं परिपतन्त्यादिभाजीनि ह्येतस्य साम्न ॥ ४ ॥
In plain words
Now, that which occurs at the time when cows gather is the beginning; to it birds are connected. Therefore those birds fly about in the sky without any physical support, sustaining themselves, because they share in the ādi of this sāman.
Close to the Sanskrit
Now that which is at the time of gathering cows, that is thebeginning; to that birds are dependent. Therefore those birds fly about in the sky without support, taking themselves along, because they share in the ādi of this sāman.