Praśna Upaniṣad · 1..6
अथादित्य उदयन्यत्प्राचीं दिशं प्रविशति तेन प्राच्यान्प्राणान्रश्मिषु संनिधत्ते यद्दक्षिणां यत्प्रतीचीं यदुदीचीं यदधो यदूर्ध्वं यदन्तरा दिशो यत्सर्वं प्रकाशयति तेन सर्वान्प्राणान्रश्मिषु संनिधत्ते
athāditya udayanyatprācīṃ diśaṃ praviśati tena prācyān prāṇān raśmiṣu sannidhatte yaddakṣiṇāṃ yatpratīcīṃ yadudīcīṃ yadadho yadūrdhvaṃ yadantarā diśo yatsarvaṃ prakāśayati tena sarvān prāṇān raśmiṣu sannidhatte
Now, when the sun rises and enters the eastern direction, with that it embraces in its rays the living beings of the east. And when it illuminates the south, the west, the north, what is below, what is above, the intermediate directions, when it illuminates everything — with that it embraces in its rays all living beings.
The metaphor expands: the sun not only illuminates, but sustains life. Its rays (raśmi) are the subtle threads through which the universal Prāṇa nourishes every living being. Without the sun, there is no life on earth — this is a biological and metaphysical fact.
The six directions mentioned (east, south, west, north, above, below) represent the complete space, the ākāśa. But there is also mention of antarā diśaḥ — the intermediate directions, the angles, suggesting totality without gaps.
In yoga practice, this relates to the expansion of Prāṇa throughout the entire body. When prāṇa flows freely, it illuminates and sustains every cell, every nāḍī, every aspect of our being. The solar raśmi are analogous to the nāḍīs of the subtle body.
The teaching is clear: we depend completely on this universal vital force. Yoga is the art of harmonizing our individuality (jīva) with this cosmic Prāṇa.