Śvetāśvatara Upaniṣad · 3..20

तं प्रतिक्षं विदित्वा य आत्मन्यात्मानं निहितं वेद तद् विद्वांस एवाहुः

taṃ pratikṣaṃ viditvā ya ātmanyātmānaṃ nihitaṃ veda tad vidvāṃsa evāhuḥ

Knowing that reflection, he who knows the Ātman established in the Ātman, that the sages declare.

The pratikṣa (reflection/image) is the appearance the Ātman takes in manifestation —like the sun reflected in water. Knowing this is seeing beyond the reflection to the source. The Ātman is “established in the Ātman” —consciousness is self-luminous, does not depend on another to shine. In our yoga practice, this is spiritual maturity: not seeking experiences, not accumulating knowledge, but resting in what has always been the case. The vidvān (sages) simply “declare” this truth, because truth needs no defense or argumentation.