Vers
 VEDA 
jñānena tu tad ajñānam yeṣāṃ nāśitam ātmanaḥ | teṣām ādityavaj jñānaṃ prakāśayati tat param
“As the sun dispels darkness and illuminates everything, so divine knowledge destroys ignorance and reveals the transcendental Absolute Truth.” — Bhagavad-Gītā 5.16    

Vaikuntha-loka – the Spiritual Sky

Vaikuntha

Kṛṣṇa is the Lord of innumerable energies, which can be divided threefold into: (1) antaraṅga-śakti (His internal energy), (2) tataṣṭha-śakti (marginal energy) and (3) bahiraṅga-śakti (external energy). The internal energy of the Lord, also called svarupa-śakti, comprises the spiritual world with its myriad realms, forms and attributes of the Lord, etc., and is divided threefold into: sandhini-śakti (sat – existential energy), samvit-śakti (cit – knowledge energy) and hladini-śakti (ānanda – pleasure energy). The marginal energy includes the living beings, the spiritual souls. It is also called jīva-śakti. The material world, where the conditioned souls, covered by ignorance, lead a sorrowful existence separate from the Supreme Lord, is a product of the external energy, also called māyā-śakti.

The manifestations of the Lord's internal energy are eternal, full of knowledge and transcendental bliss, while the manifestations of the external energy are the opposite. Individual souls have the option of seeking refuge with the inner energy or the outer energy of the Lord. If a spiritual soul seeks refuge in the external energy, it becomes covered by ignorance and continues to experience the sufferings of birth, old age, disease and death.

Devi-dhama ( the material world) is separated from vaikuntha-dhama ( the spiritual world) by a realm called viraja. Let us hear Śrī Caitanya Mahāprabhu, the Supreme Lord, describe these realms in Caitanya-caritāmṛta, Madhya-Lila, Ch. 21, Text 50-59.

"Between the spiritual and material worlds there is a body of water known as Viraja. This body of water has come into existence through the perspiration of the Supreme Personality of Godhead.”

“Beyond the Viraja river is the spiritual nature, which is indestructible, eternal, inexhaustible and unlimited. It is the supreme realm, consisting of three-fourths of the Lord's abundances. It is known as paravyoma, the spiritual sky.”

“On the other side of the Viraja River is the external realm, which is full of unlimited universes.”

“The realm of external energy is called devi-dhama and its inhabitants are conditioned souls. There resides the material energy called Durga with her many attendants.”

A.C. Bhaktivedanta Swami Prabhupada, who translated the Caitanya-Caritāmṛta into English, says in his explanation of this verse:

“Because the conditioned souls want to enjoy the material energy, they are allowed to reside in devi-dhama, where Goddess Durga, as the servant of the Supreme Lord, executes His orders. The material energy is called jagat-laksmi because it protects the confused conditioned souls. Goddess Durga is therefore called the material mother and Śrī Śiva, her consort, the material father. Durga means “fortress” and Goddess Durga is so called because this material world is like a great fortress where the conditioned souls are under her care. To gain material benefits, conditioned souls try to please her and Mother Durga provides them with all kinds of opportunities for their enjoyment. Therefore, the conditioned souls are deluded and have no desire to escape from their prison, the external energy of the Lord. So they keep making plans to live there peacefully and happily. This is the nature of the material world.”
ei tina dhamera haya kṛṣṇa adhīśvara goloka-paravyoma—prakṛtira para
“Kṛṣṇa is the supreme possessor of all dhamas including goloka-dhama, vaikuntha-dhama and devi-dhama, the material world.”

Commentary to this verse by Śrīla Prabhupada:

“When a living entity is liberated from devi-dhama but knows nothing of the opulence of hari-dhama, he is transferred to mahesa-dhama, which is between the other two dhamas. There the liberated soul does not get the opportunity to serve the Supreme Personality of Godhead; therefore mahesa-dhama, the kingdom of Śiva, although situated above devi-dhama, is not the spiritual world. The spiritual world begins with hari-dhama or vaikuntha-loka.”
cic-chakti-vibhuti-dhama—tripad-aisvarya-nama mayika vibhuti—eka-pada abhidhana
“The spiritual world is three-fourths of the energy and opulences of the Supreme Personality of Godhead, while the material world is only one-fourth of that energy.”

The energies of the Supreme Lord and their manifestations are unlimited. The material world emanates only from a spark of His splendour. In the spiritual world, there are different regions where liberated souls serve the Supreme Lord in different forms according to their inclination. When a living entity enters one of these spiritual regions through bhakti-yoga, devotional service to the Personality of Godhead, he is eternally liberated, blissful and no longer has to descend into the material world, which for the bewildered soul is nothing but ignorance, a chain of bad dreams.

“All places in the material world – from the highest planet Brahmaloka down to the lowest planet – are places of suffering, where birth and death are repeated. But he who enters My kingdom, O son of Kunti, is never reborn.”
— Bhagavad-gītā 8.16

From this point of view, how nonsensical are all the efforts of the conditioned souls in the material world to explore the material world, to improve living conditions and to become happy here?!

"I worship the transcendental realm of Goloka Vrindavana, which is self-luminous and full of bliss, where as loving consorts the goddesses of fortune in their pure spiritual essence offer loving service to the Supreme Lord Kṛṣṇa, as their only beloved, where every tree is a desire tree, where the earth is made of transcendental wish fulfilling cintamani juwels, where water is nectar, where every word is a song, where every step is a dance, where the flute is Kṛṣṇa's constant companion, where countless surabhi cows give oceans of spiritual milk, where not a single moment is wasted, because there past, present and future do not exist. This realm is known only to a few self-realised souls in this world.”
— Brahmā-Saṃhitā 5.56
“I am the origin of all spiritual and material worlds. Everything emanates from Me. The sages who have fully understood this engage in My devotional service and worship Me with all their hearts.”
— Bhagavad-gītā 10.8