….transcendental topics of the Lord act like injections when received by the sincere devotee from a person who is perfectly uncontaminated by material tinges. In other words, reception of the messages of Srimad-Bhagavatam from professional men, heard by a karma-kandiya audience, never acts miraculously as stated here. Devotional hearing of the messages of the Lord is not like hearing ordinary topics; therefore the action will be felt by the sincere hearer by experience of the gradual disappearance of ignorance….
….The crucial test of hearing Srimad Bhagavatam is that one should get positive enlightenment by such an act.

SB 2.4.5 purport