"Since Kṛṣṇa and His holy name are identical, the holy name is eternally pure and beyond material contamination. It is the Supreme Personality of Godhead as a transcendental vibration. The holy name is completely different from material sound, as confirmed by Narottama dāsa Ṭhākura: golokera prema-dhana, hari-nāma-saṅkīrtana. The transcendental vibration of hari-nāma-saṅkīrtana is imported from the spiritual world. Thus although materialists who are addicted to experimental knowledge and the so-called 'scientific method' cannot place their faith in the chanting of the Hare Kṛṣṇa mahā-mantra, it is a fact that simply by chanting the Hare Kṛṣṇa mantra offenselessly one can be freed from all subtle and gross material conditions. The spiritual world is called Vaikuṇṭha, which means 'without anxiety.' In the material world everything is full of anxiety (kuṇṭha), whereas in the spiritual world (Vaikuṇṭha) everything is free from anxiety. Therefore those who are afflicted by a combination of anxieties cannot understand the Hare Kṛṣṇa mantra, which is free from all anxiety. In the present age the vibration of the Hare Kṛṣṇa mahā-mantra is the only process that is in a transcendental position, beyond material contamination. Since the holy name can deliver a conditioned soul, it is explained here to be sarva-mantra-sāra, the essence of all Vedic hymns."
(Caitanya-caritāmṛta Ādi 7.74, Purport)
"So the sound is very important thing. The sound is the cause of our bondage in this material world. Just like in big, big cities they are attached to the sound vibrated by the cinema artist. And not only that; so many other things we are hearing through the radio message, attachment for the sound. And because it is material sound, we are becoming materially entangled, entangled more and more. Some actress, some cinema artist, singing, and people are so fond of hearing that singing that the artist is paid fifteen thousand rupees for one song. There are many here in Bombay. So just see how much attraction we have got for the material sound vibration. Similarly, the same attachment, if we turn to hear about Hare Kṛṣṇa mahā-mantra, then we become liberated. The same sound. One is material; one is spiritual. So you practice to be attached by this spiritual sound vibration, then your life will be successful.
ānandāmbudhi-vardhanaṁ prati-padaṁ pūrṇāmṛtāsvādanaṁ
paraṁ vijayate śrī-kṛṣṇa-saṅkīrtanam
(CC Antya 20.12)
So this Kṛṣṇa consciousness movement is meant for this purpose, that 'You have already attachment for sound. Now just transfer this attachment for spiritual sound. Then your life will be successful.' This is Hare Kṛṣṇa movement, teaching people how to transfer the attachment from material sound to the spiritual sound. Narottama dāsa Ṭhākura therefore sings, golokera prema-dhana, hari-nāma-saṅkīrtana, rati nā janmilo mora tāy. This sound coming from the spiritual world, golokera prema-dhana, by chanting, by hearing this sound, we shall develop all original dormant love for God. That is wanted."
(Srila Prabhupada Lecture, Bombay, January 22, 1975)
"This is the remedy. Golokera prema-dhana, this hari-nāma-saṅkīrtana, chanting of Hare Kṛṣṇa mantra, this sound vibration, it is not material. Suppose if I would have advised my disciples that 'You chant Mr. John, Mr. John, Mr. John,' this movement would not have spread. (laughter) How long one can chant this 'Mr. John, Mr. John'? Therefore it is the proof, that all over the world we have got about hundred centers. Everywhere, hundred, two hundred, three hundred disciples are there. They're chanting, dancing, with Hare Kṛṣṇa mantra. Why? Because it is not material sound vibration. This is the proof. Don't think that Hare Kṛṣṇa chanting and chanting the name of Mr. John is the same. No. This is the proof. You can go on chanting twenty-four hours, still you will not feel tired. This is the golokera... This is the proof, that this hari-nāma-saṅkīrtana, golokera prema-dhana, it is the property for loving. It is the thing which will lead you how to love God, prema-dhana. You will gradually develop your propensity to love Kṛṣṇa. Ceto-darpaṇa-mārjanam. Caitanya Mahāprabhu has said that paraṁ vijayate śrī-kṛṣṇa-saṅkīrtanam: 'All glories to the chanting of Hare Kṛṣṇa mantra.'"
(Srila Prabhupada Lecture, New York, March 6, 1975)
"We may not understand what is meaning of Hare Kṛṣṇa, but still, because it is transcendental sound, it is auspicious. Wherever you chant Hare Kṛṣṇa, they may hear or they may not hear, it is auspicious for them. So we are sending our men for street saṅkīrtana. It doesn't matter whether people are eager to hear it or not, but it is auspicious. It will create an atmosphere which is very, very congenial to the human society. That should be our principle. Not that because we are chanting, nobody is taking care, we shall not be disappointed. Our this saṅkīrtana movement is so nice that simply by chanting, the vibration will create an auspicious atmosphere."
(Srila Prabhupada Lecture, New York, April 6, 1973)
"Narottama dāsa Ṭhākura regrets, 'My Lord, I have lost or I have wasted my valuable life as human being by not accepting Kṛṣṇa consciousness. Hari hari biphale janama goṅāinu, manuṣya-janama pāiyā: 'I got this opportunity of human life, but I could not worship Rādhā-Kṛṣṇa. Therefore voluntarily, willingly, I have drunk poison.' Jāniyā śuniyā biṣa khāinu. Golokera prema-dhana, hari-nāma-saṅkīrtana, rati nā janmilo kene tāya: 'This transcendental Hare Kṛṣṇa mantra, it is not ordinary vibration. This vibration is coming from the spiritual world, but I have no attraction.'"
(Srila Prabhupada Darsana, Hyderabad, December 3, 1976)