No one can give rapt attention who is not pure in mind. No one can be pure in mind who is not pure in action. No one can be pure in action who is not pure in eating, sleeping, fearing and mating. But somehow or other if someone hears with rapt attention from the right person, at the very beginning one can assuredly see Lord Sri Krsna in person in the pages of Bhagavatam.

From Srila Prabhupada's purport to SB 1.3.44.