The Paramātmā feature of the Personality of Godhead is one of three plenary expansions, or viṣṇu-tattvas, collectively known as the puruṣa-avatāras. One of these viṣṇu-tattvas who is within the universe is known as Kṣīrodakaśāyī Viṣṇu. He is the Viṣṇu among the three principal deities-Brahmā, Viṣṇu and Śiva-and He is the all-pervading Paramātmā in each and every individual living entity. The second viṣṇu-tattva within the universe is Garbhodakaśāyī Viṣṇu, the collective Supersoul of all living entities. Beyond these two is Kāraṇodakaśāyī Viṣṇu, who lies in the Causal Ocean. He is the creator of all universes. The yoga system teaches the serious student to meet the viṣṇu-tattvas after going beyond the twenty-four material elements of the cosmic creation. The culture of empiric philosophy helps one realize the impersonal brahmajyoti, which is the glaring effulgence of the transcendental body of Lord Śrī Kṛṣṇa. That the brahmajyoti is Kṛṣṇa's effulgence is confirmed in the Bhagavad-gītā (14.27) as well as the Brahma-saṁhitā (5.40):
- yasya prabhā-prabhavato jagad-aṇḍa-koṭi-
- koṭiṣv aśeṣa-vasudhādi vibhūti-bhinnam
- tad brahma niṣkalam anantam aśeṣa-bhūtaṁ
- govindam ādi-puruṣaṁ tam ahaṁ bhajāmi
"In the millions and millions of universes there are innumerable planets, and each and every one of them is different from the others by its cosmic constitution. All of these planets are situated in a corner of the brahmajyoti. This brahmajyoti is but the personal rays of the Supreme Personality of Godhead, Govinda, whom I worship." This mantra from the Brahma-saṁhitā is spoken from the platform of factual realization of the Absolute Truth, and the śruti-mantra of Śrī Īśopaniṣad under discussion confirms this mantra as a process of realization. The Īśopaniṣad mantra is a simple prayer to the Lord to remove the brahmajyoti so that one can see His real face. This brahmajyoti effulgence is described in detail in several mantras of the Muṇḍaka Upaniṣad (2.2.10-12):