SB 5.18.11

yat-saṅga-labdhaṁ nija-vīrya-vaibhavaṁ
 tīrthaṁ muhuḥ saṁspṛśatāṁ hi mānasam
haraty ajo ’ntaḥ śrutibhir gato ’ṅgajaṁ
 ko vai na seveta mukunda-vikramam
Synonyms: 
yat — of whom (the devotees); saṅga-labdham — achieved by the association; nija-vīrya-vaibhavam — whose influence is uncommon; tīrtham — holy places like the Ganges; muhuḥ — repeatedly; saṁspṛśatām — of those touching; hi — certainly; mānasam — the dirty things in the mind; harati — vanquishes; ajaḥ — the supreme unborn one; antaḥ — in the core of the heart; śrutibhiḥ — by the ears; gataḥ — entered; aṅga-jam — dirty things or infections of the body; kaḥ — who; vai — indeed; na — not; seveta — would serve; mukunda-vikramam — the glorious activities of Mukunda, the Supreme Personality of Godhead.
Translation: 
By associating with persons for whom the Supreme Personality of Godhead, Mukunda, is the all in all, one can hear of His powerful activities and soon come to understand them. The activities of Mukunda are so potent that simply by hearing of them one immediately associates with the Lord. For a person who constantly and very eagerly hears narrations of the Lord’s powerful activities, the Absolute Truth, the Personality of Godhead in the form of sound vibrations, enters within his heart and cleanses it of all contamination. On the other hand, although bathing in the Ganges diminishes bodily contaminations and infections, this process and the process of visiting holy places can cleanse the heart only after a long time. Therefore who is the sane man who will not associate with devotees to quickly perfect his life?
Purport: 

Bathing in the Ganges can certainly cure one of many infectious diseases, but it cannot cleanse one’s materially attached mind, which creates all kinds of contaminations in material existence. However, one who directly associates with the Supreme Lord by hearing of His activities cleanses the dirt from his mind and very soon comes to Kṛṣṇa consciousness. Sūta Gosvāmī confirms this in Śrīmad-Bhāgavatam (1.2.17):

śṛṇvatāṁ sva-kathāḥ kṛṣṇaḥ
 puṇya-śravaṇa-kīrtanaḥ
hṛdy antaḥ-stho hy abhadrāṇi
 vidhunoti suhṛt-satām

The Supreme Lord within everyone’s heart becomes very pleased when a person hears narrations of His activities, and He personally cleanses the dirt from the mind of the listener. Hṛdy antaḥ-stho hy abhadrāṇi vidhunoti: He washes off all dirt from the mind. Material existence is caused by dirty things within the mind. If one can cleanse his mind, he immediately comes to his original position of Kṛṣṇa consciousness, and thus his life becomes successful. Therefore all the great saints in the devotional line very strongly recommend the process of hearing. Śrī Caitanya Mahāprabhu introduced the congregational chanting of the Hare Kṛṣṇa mantra to give everyone a chance to hear Kṛṣṇa’s holy name, for simply by hearing Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare, one becomes purified (ceto-darpaṇa-mārjanam). Therefore our Kṛṣṇa consciousness movement is chiefly engaged in chanting the Hare Kṛṣṇa mantra all over the world.

After one’s mind becomes cleansed by chanting Hare Kṛṣṇa, one gradually comes to the platform of Kṛṣṇa consciousness and then reads books like Bhagavad-gītā, Śrīmad-Bhāgavatam, Caitanya-caritāmṛta and The Nectar of Devotion. In this way, one becomes more and more purified of material contamination. As stated in Śrīmad-Bhāgavatam (1.2.18):

naṣṭa-prāyeṣv abhadreṣu
 nityaṁ bhāgavata-sevayā
bhagavaty uttama-śloke
 bhaktir bhavati naiṣṭhikī

“By regularly hearing the Bhāgavatam and rendering service unto the pure devotee, all that is troublesome to the heart is practically destroyed, and loving service unto the glorious Lord, who is praised with transcendental songs, is established as an irrevocable fact.” In this way, simply by hearing of the powerful activities of the Lord, the devotee’s heart becomes almost completely cleansed of material contamination, and thus his original position as an eternal servant who is part and parcel of the Lord becomes manifest. While the devotee engages in devotional service, the passionate and ignorant modes of material nature are gradually vanquished, and then he acts only in the mode of goodness. At that time he becomes happy and gradually advances in Kṛṣṇa consciousness.

All the great ācāryas strongly recommend that people be given a chance to hear about the Supreme Lord. Then success is assured. The more we cleanse the dirt of material attachment from our hearts, the more we will be attracted by Kṛṣṇa’s name, form, qualities, paraphernalia and activities. This is the sum and substance of the Kṛṣṇa consciousness movement.