tam uddhava nibodha me
The word naiḥśreyasa-kara indicates that which awards the highest perfection of life, Kṛṣṇa consciousness, which the Lord is explaining to Śrī Uddhava. When considering religious principles, ordinary human beings remain bogged down in sectarian mundane considerations. The process that awards the highest perfection of life should be considered the most auspicious for human beings. The varṇāśrama system is the most scientific presentation of religiosity on the earth, and those who are most perfect in that system come to the point of Kṛṣṇa consciousness, or dedicating everything for the satisfaction of the Supreme Lord.