The materially absorbed conditioned soul can be cured by Kṛṣṇa consciousness as set forth here in the Gītā. This process is generally known as yajña, or activities (sacrifices) simply meant for the satisfaction of Viṣṇu, or Kṛṣṇa. The more the activities of the material world are performed in Kṛṣṇa consciousness, or for Viṣṇu only, the more the atmosphere becomes spiritualized by complete absorption. The word brahma (Brahman) means "spiritual." The Lord is spiritual, and the rays of His transcendental body are called brahma-jyotir, His spiritual effulgence. Everything that exists is situated in that brahma-jyotir, but when the jyoti is covered by illusion (māyā) or sense gratification, it is called material.
(Bhagavad-Gita----4:24---purport).

It is by great fortune that one comes to Kṛṣṇa consciousness on the path of bhakti-yoga to become well situated according to the Vedic direction. The ideal yogī concentrates his attention on Kṛṣṇa who is called Śyāmasundara, who is as beautifully colored as a cloud, whose lotuslike face is as effulgent as the sun, whose dress is brilliant with jewels and whose body is flower-garlanded. Illuminating all sides is His gorgeous luster, which is called the brahma-jyotir. He incarnates in different forms such as Rāma, Nṛsiṁha, Varāha and Kṛṣṇa, the Supreme Personality of Godhead, and He descends like a human being, as the son of mother Yaśodā, and He is known as Kṛṣṇa, Govinda and Vāsudeva. He is the perfect child, husband, friend and master, and He is full with all opulences and transcendental qualities. If one remains fully conscious of these features of the Lord, he is called the highest yogi.
(Bhagavad-Gita----6:47---purport).

The light of the sun and the moon is also originally emanating from the brahma-jyotir, which is the impersonal effulgence of the Lord. And praṇava, or the oṁkāra transcendental sound in the beginning of every Vedic hymn, addresses the Supreme Lord. Because the impersonalists are very much afraid of addressing the Supreme Lord Kṛṣṇa by His innumerable names, they prefer to vibrate the transcendental sound oṁkāra. But they do not realize that oṁkāra is the sound representation of Kṛṣṇa. The jurisdiction of Kṛṣṇa consciousness extends everywhere, and one who knows Kṛṣṇa consciousness is blessed. Those who do not know Kṛṣṇa are in illusion, and so knowledge of Kṛṣṇa is liberation, and ignorance of Him is bondage.
(Bhagavad-Gita----7:8---purport).

"O my Lord, You are the maintainer of the entire universe, and devotional service to You is the highest religious principle. Therefore, I pray that You will also maintain me. Your transcendental form is covered by the yoga-māyā. The brahma-jyotir is the covering of the internal potency. May You kindly remove this glowing effulgence that impedes my seeing Your sac-cid-ānanda-vigraha (Bs. 5.1), Your eternal form of bliss and knowledge." The Supreme Personality of Godhead in His transcendental form of bliss and knowledge is covered by the internal potency of the brahma-jyotir, and the less intelligent impersonalists cannot see the Supreme on this account.
(Bhagavad-Gita----7:25---purport).

This devotional service is just like a seed, and if it is sown in the heart of a living entity, and if he goes on hearing and chanting Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare, that seed fructifies, just as the seed of a tree fructifies with regular watering. The spiritual plant of devotional service gradually grows and grows until it penetrates the covering of the material universe and enters into the brahma-jyotir effulgence in the spiritual sky. In the spiritual sky also that plant grows more and more until it reaches the highest planet, which is called Goloka Vṛndāvana, the supreme planet of Kṛṣṇa. Ultimately, the plant takes shelter under the lotus feet of Kṛṣṇa and rests there. Gradually, as a plant grows fruits and flowers, that plant of devotional service also produces fruits, and the watering process in the form of chanting and hearing goes on. This plant of devotional service is fully described in the Caitanya-caritāmṛta (Madhya-līlā, Chapter Nineteen). It is explained there that when the complete plant takes shelter under the lotus feet of the Supreme Lord, one becomes fully absorbed in love of God; then he cannot live even for a moment without being in contact with the Supreme Lord, just as a fish cannot live without water. In such a state, the devotee actually attains the transcendental qualities in contact with the Supreme Lord.
(Bhagavad-Gita----10:9---purport).

The Supersoul, the Supreme Personality of Godhead, is the source of light in all luminous objects like the sun, moon and stars. In the Vedic literature we find that in the spiritual kingdom there is no need of sun or moon, because the effulgence of the Supreme Lord is there. In the material world that brahma-jyotir, the Lord's spiritual effulgence, is covered by the mahat-tattva, the material elements; therefore in this material world we require the assistance of sun, moon, electricity, etc., for light. But in the spiritual world there is no need of such things. It is clearly stated in the Vedic literature that because of His luminous effulgence, everything is illuminated. It is clear, therefore, that His situation is not in the material world. He is situated in the spiritual world, which is far, far away in the spiritual sky. That is also confirmed in the Vedic literature. Āditya—varṇaṁ tamasaḥ parastāt (Śvetāśvatara Upaniṣad 3.8). He is just like the sun, eternally luminous, but He is far, far beyond the darkness of this material world.
(Bhagavad-Gita----13:18---purport).

In the Bhagavad-gītā it is said that the brahma-jyotir, or the glowing transcendental effulgence, is resting on Lord Śrī Kṛṣṇa. In other words, the glowing effulgence known as brahma-tejas is nothing but the rays of the Lord, just as the sun rays are rays of the sun disc. So this Brahma weapon also, although materially irresistible, could not surpass the supreme strength of the Lord. The weapon called brahmāstra, released by Aśvatthāmā, was neutralized and foiled by Lord Śrī Kṛṣṇa by His own energy; that is to say, He did not wait for any other's help because He is absolute.
(Srimad Bhagavatam----1:8:15----purport).

The jñānīs and yogīs enter into the impersonal rays of the Supreme, but the bhaktas enter into the spiritual planets known as the Vaikuṇṭhas. In these spiritual planets the Supreme Lord as Nārāyaṇa predominates, and the healthy, unconditioned living beings live there by rendering loving service to the Lord in the capacity of servant, friend, parents and fiancee. There the unconditioned living beings enjoy life in full freedom with the Lord, whereas the impersonalist jñānīs and yogīs enter into the impersonal glowing effulgence of the Vaikuṇṭha planets. The Vaikuṇṭha planets are all self-illuminating like the sun, and the rays of the Vaikuṇṭha planets are called the brahma-jyotir. The brahma-jyotir is spread unlimitedly, and the material world is but a covered portion of an insignificant part of the same brahma-jyotir. This covering is temporary, and therefore it is a sort of illusion.
(Srimad Bhagavatam----1:9:44----purport).

The Supreme Personality of Godhead Lord Śrī Kṛṣṇa is described in the Bhagavad-gītā as puruṣottama, or the Supreme Personality. It is He only who can award liberation to the impersonalists by absorbing such aspirants in the brahma-jyotir, the bodily rays of the Lord. The brahma-jyotir is not separate from the Lord, as the glowing sun ray is not independent of the sun disc. Therefore one who desires to merge into the supreme impersonal brahma-jyotir must also worship the Lord by bhakti-yoga, as recommended here in the Śrīmad-Bhāgavatam. Bhakti-yoga is especially stressed here as the means of all perfection. In the previous chapters it has been stated that bhakti-yoga is the ultimate goal of both karma-yoga and jñāna-yoga, and in the same way in this chapter it is emphatically declared that bhakti-yoga is the ultimate goal of the different varieties of worship of the different demigods. Bhakti-yoga, thus being the supreme means of self-realization, is recommended here. Everyone must therefore seriously take up the methods of bhakti-yoga, even though one aspires for material enjoyment or liberation from material bondage.
(Srimad Bhagavatam----2:3:10----purport).

"I serve the Supreme Personality of Godhead Govinda, the primeval Lord, whose transcendental bodily effulgence, known as the brahma-jyotir, which is unlimited, unfathomed and all-pervasive, is the cause of the creation of unlimited numbers of planets, etc., with varieties of climates and specific conditions of life."
The same statement is in the Bhagavad-gītā (14.27). Lord Kṛṣṇa is the background of the brahma-jyotir (brahmaṇo hi pratiṣṭhāham). In the Nirukti, or Vedic dictionary, the import of pratiṣṭhā is mentioned as "that which establishes." So the brahma-jyotir is not independent or self-sufficient. Lord Śrī Kṛṣṇa is ultimately the creator of the brahma-jyotir, mentioned in this verse as sva-rociṣā, or the effulgence of the transcendental body of the Lord. This brahma-jyotir is all-pervading, and all creation is made possible by its potential power; therefore the Vedic hymns declare that everything that exists is being sustained by the brahma-jyotir (sarvaṁ khalv idaṁ brahma). Therefore the potential seed of all creation is the brahma-jyotir, and the same brahma-jyotir, unlimited and unfathomed, is established by the Lord. Therefore the Lord (Śrī Kṛṣṇa) is ultimately the supreme cause of all creation (ahaṁ sarvasya prabhavaḥ (B.G.10:8).
(Srimad Bhagavatam----2:5:11----purport).

The universal form of the Lord, or the impersonal feature of the Lord known as the brahma-jyotir, is clearly explained here and compared to the radiation of the sun. The sunshine may expand all over the universe, but the source of the sunshine, namely the sun planet or the deity known as Sūrya-nārāyaṇa, is the basis of such radiation. Similarly, the Supreme Personality of Godhead Lord Kṛṣṇa is the basis of the impersonal brahma-jyotir radiation, or the impersonal feature of the Lord. This is confirmed in the Bhagavad-gītā (14.27). So the universal form of the Lord is the secondary imagination of the impersonal form of the Lord, but the primary form of the Lord is Śyāmasundara, with two hands, playing on His eternal flute.
(Srimad Bhagavatam----2:6:17----purport).

The only way to understand the Lord as He is, is by devotional service to the Lord, or by approaching the devotee of the Lord who always has the Lord in his heart. By devotional perfection one can understand that the impersonal brahma-jyotir is only a partial representation of the Supreme Personality of Godhead, Lord Kṛṣṇa, and that the three puruṣa expansions in the material creation are His plenary portions. In the spiritual sky of the brahma-jyotir there is no change of various kalpas or millenniums, and there are no creative activities in the Vaikuṇṭha worlds. The influence of time is conspicuous by its absence. The rays of the transcendental body of the Lord, the unlimited brahma-jyotir, are undeterred by the influence of material energy. In the material world also, the initial creator is the Lord Himself. He brings about the creation of Brahmā, who becomes the subsequent creator, empowered by the Lord.
(Srimad Bhagavatam----3:9:3----purport).