With this shloka, Chapter 15 begins a new subsection.

From 15.7 to 15.11, Bhagavān taught that Brahman alone is present in every living being as the jīva. The living body is not alive by itself; the body-mind is enlivened by reflected consciousness, and that reflected consciousness depends on Brahman. That was the first part of Brahmaṇaḥ sarvātmakatvam — Brahman as the essence of all living beings.

From 15.12 onward, the teaching expands. Brahman is not only present as the jīva in living beings. Brahman alone is also present as the jagat, the inert universe. The entire creation is not separate from Bhagavān because the cause alone appears as the effect. Just as gold alone appears as all ornaments, and wood alone appears as furniture, Bhagavān, being the cause of the universe, alone appears as the universe. If Bhagavān had to list every object one by one — table, chair, mountain, river, body, star, plant, stone — the chapter would never end. Therefore Bhagavān takes a few important samples from creation and says: see these powers as Mine.

In 15.12, Bhagavān selects three fundamental natural forces: sūrya-tejas, the power of the sun; candra-tejas, the power of the moon; and agni-tejas, the power of fire. These are not small or optional features of the world. They are basic, constantly experienced, and essential for the world’s survival. The more one studies them, the more one is meant to admire the intelligence and power behind creation.

The verse begins: yat āditya-gataṃ tejaḥ — the light or energy present in the sun. Āditya means the sun. Gatam means located in, present in, or obtaining in. Tejas means light, brilliance, energy, or power. The sun’s light illumines the world. During the day, one portion of the earth is lit by the sun without any human effort. We need many lamps and electricity to illumine a small hall, but the sun illumines vast areas of the earth. The sun’s energy does not get “fused out” like a bulb. Its very existence sustains life on earth. The Vedic tradition therefore begins the day with reverence to the sun, and many daily prayers include sūrya-upāsanā.

Then Bhagavān says: yad candramasi — the light that is in the moon. The moon’s light is borrowed from the sun, but even reflected light is powerful. On a clear full-moon night, moonlight can illumine the world gently. The moon also has a cooling, nourishing, and rhythmic significance in the natural order. Swami notes that even this reflected light has glory; therefore that candra-śakti, the lunar power, is also to be understood as Bhagavān’s power.

Then: yac ca agnau — the light and power present in fire. Fire is not only a flame used for cooking or worship. Agni represents heat, transformation, energy, and the power that makes many processes possible. Here, Bhagavān first points to the external fire principle, bāhya-agni, which cooks, warms, transforms, and illumines. In the next verses, the teaching will go further into earth, plants, food, and digestive fire. But here, the main point is that agni-tejas too is Bhagavān’s manifestation.

The sentence concludes: tat tejaḥ viddhi māmakam — know that light, that energy, to be Mine. Māmakam means “belonging to Me,” “My own.” This does not mean Bhagavān is one entity sitting elsewhere and separately owning the sun’s light like property. Rather, the power by which the sun shines, the moon reflects, and fire burns is not separate from Bhagavān. The natural forces of the universe are Bhagavān’s manifestations.

This shloka also must be distinguished from 15.6. In 15.6, Bhagavān said that Brahman is not illumined by the sun, moon, or fire. There, the teaching was about Brahman as pure consciousness, the subject that cannot be objectified by any light. Here, in 15.12, the teaching is different. Now Bhagavān points to the lights within the universe and says: their power too is Mine. In 15.6, Brahman is the consciousness because of which sun, moon, and fire are known. In 15.12, sun, moon, and fire are shown as manifestations of Bhagavān within the jagat.

So the movement is subtle and beautiful. First, do not mistake the sun, moon, and fire as illumining Brahman. Brahman, as consciousness, makes them known. Then, once that is understood, do not dismiss the sun, moon, and fire as ordinary inert things. Their very energy is Bhagavān’s manifestation. The wise person therefore sees Bhagavān both as the consciousness because of which the world is known and as the power manifesting through the world itself.