यदादित्यगतं तेजो जगद्भासयतेऽखिलम् ।
यच्चन्द्रमसि यच्चाग्नौ तत्तेजो विद्धि मामकम् ॥ १५.१२ ॥

yad-ādityagatam tejo jagad-bhāsayate’khilam |
yac-candramasi yaccāgnau tat-tejo viddhi māmakam || 15.12 ||

Power that creates external visibles

After emphasizing that spiritual search and seeking is truly inner and the resulting discovery is also inner, Krishna speaks about the inner presence, its vast and manifold magnitude and splendour. This elaboration is very important. It is not that the seeker comprehends the spiritual splendour only within himself. He can and should visualize it all around:

Know the brilliance of the sun that illumines the world, that (brilliance) which is in the moon and the fire, to be of the same Supreme.

The brilliance of the sun, providing heat and light to the whole earth is due to the supreme splendour of the inner Soul. The same is the truth about the moon, fire and similar luminaries also. In other words, one should not think that the Soul is only an inner spiritual magnificence, having no bearing upon the world of matter and energy. Every speck of material existence as well as the flow of energy, no matter where it occurs or is evident, is an emanation from the Self, the Soul, and none else.