Simply by devotional service one becomes purified, even he is born in the family of the dog-eaters. That is the Vedic version. Caitanya Mahāprabhu quotes from Śrīmad-Bhāgavatam. Ataeva bhakti kṛṣṇa prāptyera (CC Madhya 20.139). Therefore He concludes that "If you want at all Kṛṣṇa . . ." Kṛṣṇa . . . we should, everyone should want Kṛṣṇa. Because as soon as we get Kṛṣṇa . . . yaṁ labdhvā cāparaṁ lābhaṁ manyate nādhikaṁ tataḥ (BG 6.22). If actually we get Kṛṣṇa, then we shall not consider any other profit more valuable than Kṛṣṇa.
Just like Dhruva Mahārāja. Dhruva Mahārāja went to practice yoga in the forest, Madhuvana. The idea was to get the kingdom of his father. Now, actually when he saw Kṛṣṇa, Viṣṇu . . . The picture is here; you can see. Actually when he saw by severe austerities and penances, a small boy, five-years-old boy, then he said: "My dear Lord, now when You offer benediction that 'You take whatever benediction you want, you take from Me,' " he said, svamin kṛtārtho 'smi varaṁ na yāce (CC Madhya 22.42). That is the process. If one gets Kṛṣṇa, he thinks that no more any other benediction is required. He becomes fully satisfied. Svāmin kṛtārtho 'smi: "I am fully satisfied." Therefore we find a kṛṣṇa-bhakta is always satisfied, because he has no demand.