In the Garuḍa Purāṇa the stress on hearing is expressed very nicely. It is said there: "The state of conditioned life in the material world is just like a man lying unconscious, having been bitten by a snake. This is because both such unconscious states can be ended by the sound of a mantra." When a man is snake-bitten he does not die immediately, but first becomes unconscious and remains in a comatose condition. Anyone who is in the material world is also sleeping, as he is ignorant of his actual self or his actual duty and his relationship with God. So materialistic life means that one is bitten by the snake of māyā, illusion, and thus, without any Kṛṣṇa consciousness, he is almost dead. Now the so-called dead man bitten by a snake can be brought back again to life by the chanting of some mantra. There are expert chanters of these mantras who can perform this feat. Similarly, one can be brought back into Kṛṣṇa consciousness from the deadly unconscious state of material life by hearing of the mahā-mantra: Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare.
In the Fourth Canto of Śrīmad-Bhāgavatam, 29th Chapter, 37th verse, the importance of hearing of the pastimes of the Lord is stated by Śukadeva Gosvāmī to Mahārāj Parīkṣit: "My dear King, one should stay at a place where the great ācāryas (holy teachers) speak about the transcendental activities of the Lord, and one should give aural reception to the nectarean river flowing from the moonlike faces of such great personalities. If someone eagerly continues to hear such transcendental sounds, then certainly he will become freed from all material hunger, thirst, fear and lamentation, as well as all illusions of material existence."
Śrī Caitanya Mahāprabhu also recommended this process of hearing as a means of self realization in the present age of Kali. In this age it is very difficult to follow thoroughly the regulative principles and studies of the Vedas which were formerly recommended. However, if one gives aural reception to the sound vibrated by great devotees and ācāryas, that alone will give him relief from all material contamination. Therefore it is the recommendation of Caitanya Mahāprabhu that one should simply hear from authorities who are actually devotees of the Lord. Hearing from professional men will not help. If we hear from those who are actually self realized, then the nectarean rivers, like those which are flowing on the moon planet, will flow into our ears. This is the metaphor used in the above verse.
As is stated in the Bhagavad-gītā, "A materialistic person can give up his material hankerings only by becoming situated in Kṛṣṇa consciousness." Unless one finds a superior engagement he will not be able to give up his inferior engagement. In the material world everyone is engaged in the illusory activities of inferior energy, but when one is given the opportunity to relish the activities of the superior energy performed by Kṛṣṇa, then he forgets all his lesser pleasures. When Kṛṣṇa speaks on the battlefield of Kurukṣetra, to the materialistic person it appears that this is simply talk between two friends, but actually it is a river of nectar flowing down from the mouth of Śrī Kṛṣṇa. Arjuna gave aural reception to such vibrations, and thus he became freed from all the illusions of material problems.