Śvetāśvatara Upaniṣad · 1..4
तदेवाग्निस्तदादित्यस्तद्वायुस्तदु चन्द्रमाः तदेव शुक्रमन्नं चैव तदेव मनो मanas च तद्वाक् तदेवामात्मेन्द्रियाणि चाप्यहुः
tadevāgnistadādityastadvāyustadu candramāḥ tadeva śukramannaṃ caiva tadeva mano manasaśca tadvāk tadevātmendriyāṇi cāpyahuḥ
That itself is the fire, that is the sun, that is the wind, that is the moon; that is the pure, that is the mind and that is the intellect; that is speech, that is the ego and that are the senses.
A powerful declaration of non-duality: the same Brahman manifests as all the elements and faculties we experience. Fire (agni), the sun (āditya), the wind (vāyu) are not merely external forces but modalities of the One Reality. In our yoga practice, we understand that the mind (manas), intellect, and senses are not obstacles but divine instruments when recognized as expressions of the One. The division between inside and outside dissolves; the Ātman that presides within is the same that shines in the outer sun.