Those who are on the modes of goodness of material nature, they go higher and higher, higher and higher. But Kṛṣṇa says, ā-brahma-bhuvanāl lokāḥ punar āvartino 'rjuna (BG 8.16): even if you go to the Brahmaloka, that is also not security that you get rid of the four principles of material life, birth, death, old age and disease. Ā-brahma-bhuvanāl lokāḥ punar āvartino 'rjuna. Again coming down. Āruhya kṛcchreṇa para . . . even if you go to the impersonal Brahman effulgence, from there also, you have to come back. Āruhya kṛcchreṇa paraṁ padaṁ tataḥ patanty adhaḥ (SB 10.2.32). So, madhya-dhāma gatvā punar janma na . . . but anyone who reaches . . .
The jīva, another reason of falling down . . . there is sometimes question, "How one who lived in association with Kṛṣṇa, how he fell down?" Generally, those who are living with Kṛṣṇa or Vaikuṇṭha, they never fall down. But those who are in the effulgence of Kṛṣṇa, in the impersonal Brahman, they fall down, because it is the propensity of the living entity to enjoy. But one cannot enjoy; there is no ānanda.
Those who are merging in the Brahman effulgence, they are getting the department of eternity. The Brahman is sac-cid-ānanda. So they are simply accepting sad-aṁśa. Sad-aṁśa means only eternity. Just like if you are asked to sit down in a place eternally, no, it will be impossible. You must desire a change, variety, because we are living entity, living being. So therefore our Vaiṣṇava philosophy has varieties of enjoyment.