The comparison made here is very interesting. Kṛṣṇa does not grow like an ordinary human being, even though He exhibits His pastimes of childhood, boyhood and pre-youth. When He reaches the age of pre-youth, kaiśora, He does not grow any older. He simply remains in His kaiśora age. He is therefore described in the Brahma-saṁhitā (BS 5.38) as nava-yauvana:
- advaitam acyutam anādim ananta-rūpam
- ādyaṁ purāṇa-puruṣaṁ nava-yauvanaṁ ca
- vedeṣu durlabham adurlabham ātma-bhaktau
- govindam ādi-puruṣaṁ tam ahaṁ bhajāmi
This nava-yauvana, or pre-youth, is the eternal transcendental form of Kṛṣṇa. Kṛṣṇa never grows older than nava-yauvana.