Actually, although Kṛṣṇa was acting so wonderfully, Mahārāja Nanda and mother Yaśodā could not think of Him as the Supreme Personality of Godhead. Instead, they always accepted Him as their beloved child. Thus Nanda Mahārāja did not accept the fact that Varuṇa worshiped Kṛṣṇa because He is the Supreme Personality of Godhead; rather he took it that because Kṛṣṇa was such a wonderful child He was respected even by Varuṇa. The friends of Nanda Mahārāja, all the cowherd men, became eager to know if Kṛṣṇa was actually the Supreme Personality and if He was going to give them all salvation. When they were all thus consulting among themselves, Kṛṣṇa understood their minds, and in order to assure them of their destiny in the spiritual kingdom, He showed them the spiritual sky. Generally, ordinary persons are engaged simply in working hard in the material world, and they have no information that there is another kingdom or another sky, which is known as the spiritual sky, where life is eternal, blissful and full of knowledge. As it is stated in the Bhagavad-gītā, a person returning to that spiritual sky never returns to this material world of death and suffering.
Kṛṣṇa, the Supreme Personality of Godhead, is always eager to give information to the conditioned soul that there is a spiritual sky far, far beyond this material sky, transcendental to the innumerable universes created within the total material energy. Kṛṣṇa is, of course, always very kind to every conditioned soul, but, as stated in the Bhagavad-gītā, He is especially inclined to the pure devotees. Hearing their inquiries, Kṛṣṇa immediately thought that His devotees in Vṛndāvana should be informed of the spiritual sky and the Vaikuṇṭha planets therein.
Within the material world, every conditioned soul is in the darkness of ignorance. This means that all conditioned souls are under the concept of bodily existence. Everyone is under the impression that he is of this material world, and with this concept of life everyone is working in ignorance in different forms of life. The activities of the particular type of body are called karma, or fruitive action. All conditioned souls, being under the impression of the bodily concept, are working according to their particular type of body. These activities are creating their future conditioned life. Because they have very little information of the spiritual world, they do not generally take to spiritual activities, which are called bhakti-yoga. Those who successfully practice bhakti-yoga go directly to the spiritual world after giving up this present body, and there they become situated in one of the Vaikuṇṭha planets. The inhabitants of Vṛndāvana are all pure devotees. Their destination after quitting the body is Kṛṣṇaloka. They even surpass the Vaikuṇṭhalokas. The fact is that those who are always engaged in Kṛṣṇa consciousness and mature, pure devotional service are given the chance, after death, to gain Kṛṣṇa’s association in one of the universes within the material world. Kṛṣṇa’s pastimes are continuously going on, either in this universe or in another universe. Just as the sun globe is passing over many places across this earthly planet, so kṛṣṇa-līlā, or the transcendental advent and pastimes of Kṛṣṇa, are also going on continuously, either in this or another universe. The mature devotees, who have completely executed Kṛṣṇa consciousness, are immediately transferred to the universe where Kṛṣṇa is appearing. In that universe the devotees get their first opportunity to associate with Kṛṣṇa personally and directly. The training goes on, as we see in the vṛndāvana-līlā of Kṛṣṇa within this planet. Kṛṣṇa therefore revealed the actual features of the Vaikuṇṭha planets so that the inhabitants of Vṛndāvana could know their destination.
Thus Kṛṣṇa showed them the eternal, ever-existing spiritual sky, which is unlimited and full of knowledge. Within this material world there are different grades of forms, and according to the grade, knowledge is proportionately manifested. For example, the knowledge in the body of a child is not as perfect as the knowledge in the body of an adult man. Everywhere there are different grades of living entities—in aquatic animals, in the plants and trees, in the reptiles and insects, in birds and beasts and in the civilized and uncivilized human forms of life. Above the human form of life there are demigods, Cāraṇas and Siddhas on up to Brahmaloka, where Lord Brahmā lives, and among these demigods there are always different grades of knowledge. But past this material world, in the spiritual sky, everyone is in full knowledge, and therefore all the living entities there are engaged in devotional service to the Lord, either in the Vaikuṇṭha planets or in Kṛṣṇaloka.