BG Chap 13 - The Paramātmā's svarūpa -Source of all light
He is the light of all luminaries like the sun, and is beyond the darkness of matter. The sun, moon, stars, fire and lightning all shine only by following the shining Lord. His light illuminates all these. He is not touched by prakṛti. The śruti says āditya-varṇaṁ tamasaḥ parastāt: He is like the sun beyond darkness. He is pure, unchanging knowledge. The śruti says Brahman is knowledge and condensed bliss. Jñānam means that which is revealed by the function of intelligence. The Lord is that jñānam, who is to be realized (jñeyam) by the person desiring liberation, as the worthy object of surrender. Thus He is the object of knowledge. He is what is to be known which, in matured state, must have form and other qualities. He is attained by the process of knowledge (pridelessness etc).