Bhagavad Gita · Chapter 13: The Field and the Knower of the Field
Bhagavad Gita 13.17
ज्योतिषामपि तज्ज्योतिस्तमसः परमुच्यते ।
ज्ञानं ज्ञेयं ज्ञानगम्यं हृदि सर्वस्य विष्ठितम् ॥
jyotiṣāmapi tajjyotistamasaḥ paramucyate | jñānaṃ jñeyaṃ jñānagamyaṃ hṛdi sarvasya viṣṭhitam ||
It is the light of all lights, and is said to be beyond darkness. It is knowledge, what is to be known, and what is reached through knowledge, seated in the heart of everyone.
Modern context
The light of all lights, beyond darkness, seated in the heart of everyone. Every light we know, sun, fire, lamp, is seen by something. That something is awareness, the light by which all other lights are known. And it is not far away; it is seated in the heart of every person. The deepest light is the one within.