Jyoti. Jyoti means light. There are different types of light. There is lamp. There is candle. There is electric bulb. The power also, they are different powers: hundred power, fifty powers, twenty-five . . . there are different grades of jyoti.
But there is supreme jyoti. Just like this moon. Moon, this night is full moon. This moon has got its illumination, but where from this illumination comes? It comes from the sunshine. The sunshine is reflected on the moon, and the moon has become illuminating source. Just like in a mirror when there is reflection of the sunshine, the mirror can also reflect another dark place; not independently. Everyone . . . in childhood everyone has played with a mirror. Just put a mirror in front of the sunshine, and the reflection is there, and you can pass on the reflection in the darkest place and it will be illuminated. Have you got experience? Yes. Similarly, neither the mirror has got reflection, neither the dark place can be illuminated by the mirror. But when the sunshine is there on the mirror, the mirror acts as illuminating agent, and it dissipates the darkness of a corner.
So sunshine is the source of all light. In the material world we have got experience that sunshine, jyoti, prakāśa. But wherefrom the sunshine comes? Sunshine is also reflection of another jyoti, or illumination. That illumination is called brahma-jyotir. And where from that brahma-jyotir emanates? That emanates from Kṛṣṇa. Just like the sunshine is emanation from the sun globe, and the sun globe is fiery, illuminated, on account of the persons within the sun globe. They have got some bodily rays. That rays is emanating from their body. Therefore the whole sun planet looks like fiery planet. And from there the illumination comes, and it is reflecting on the moon, and the moon is illuminating the whole dark night. This is called pūrṇimā. So one is borrowing the illumination from the other. But there is the supreme source of illumination. That is Kṛṣṇa.
That is confirmed in the Brahma-saṁhitā: yasya prabhā prabhavato jagad-aṇḍa-koṭi (Bs. 5.40). Yasya prabhā, the bodily rays of Kṛṣṇa, being illuminated . . . in that illumination, which is called brahma-jyotir, there are innumerable Vaikuṇṭha planets. The Vaikuṇṭha planets are self-illuminating. Therefore in the spiritual world there is no darkness. Tamasaḥ para. Therefore is said here that taj jyotis tamasaḥ param ucyate: "That spiritual world is beyond this material world." This material world is called tamaḥ. Tamaḥ means darkness. Just like this night, it is darkness. Why it is darkness? By nature it is dark. Simply by the sunshine, moonshine, electricity, we keep it brightened for some time. Otherwise, by nature it is darkness.
Similarly, there is another world, paras tasmāt tu bhāvaḥ anyaḥ (BG 8.20), another cosmic manifestation, spiritual cosmic manifestation, where there is no need of sunshine. Na tad bhāsayate sūryo na śaśāṅko na pāvakaḥ (BG 15.6). There is no need of sunshine, there is no need of moonshine, as here in this darkness, material world, there is arrangement by God to illuminate the darkness of this world. There is sun; there is moon; there is electricity; there is fire. But in the spiritual world, which is tamasaḥ para, which is beyond this darkness of this material world, there is jyoti. Therefore here it is said, jyotiṣām api taj jyotiḥ, param. There are different kinds of illumination—sunshine, moonshine, electricity, fire—but that jyoti which is directly emanating from Kṛṣṇa's body, that is the real jyoti.