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Srimad-Bhagavatam 4.4.6

Why we should come together for kirtan
Sankirtana−yajna is the proper yajna for the Kali−yuga: When learned sages and brāhmaṇas assemble to chant Vedic mantras, some of them also engage in arguing about the conclusion of the scriptures. Thus some of the sages and brāhmaṇas were arguing, and some of them were chanting the Vedic mantras, so the entire atmosphere was surcharged with transcendental sound vibration. This transcendental sound vibration has been simplified in the transcendental vibration Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare. In this age, no one is expected to be highly educated in the Vedic ways of understanding because people are very slow, lazy and unfortunate. Therefore Lord Caitanya has recommended the sound vibration Hare Kṛṣṇa, and in the Śrīmad-Bhāgavatam (11.5.32) it is also recommended: yajñaiḥ saṅkīrtana-prāyair yajanti hi sumedhasaḥ.

At the present moment it is impossible to gather sacrificial necessities because of the poverty of the population and their lack of knowledge in Vedic mantras. Therefore for this age it is recommended that people gather together and chant the Hare Kṛṣṇa mantra to satisfy the Supreme Personality of Godhead, who is accompanied by His associates. Indirectly this indicates Lord Caitanya, who is accompanied by His associates Nityānanda, Advaita and others. That is the process of performing yajña in this age.

So why do we stay apart when we should come together?

Conversation – July 13, 1975, Philadelphia

Prof. Hopkins: So you would see the Bhagavad-gītā then as accessible to a wide range of people, at an elementary level or beginning level, whereas Śrīmad-Bhāgavatam would be for more advanced, more advanced people.

Prabhupāda: Not only advanced, completely advanced. Because so long one will be, stay on the material platform, he will be envious of others only, animal propensity, dog. Dog does not like another dog is coming. So unless one is spiritually realized, the dog mentality will remain there. It is said nāsau munir yasya mataṁ na bhinnam, even amongst the topmost thinkers, if he does not refute other thinkers, he is not a good thinker. That enviousness. He will not be established a good thinker if he cannot… If a scientist, if he cannot refute the previous scientist, he is not a scientist. This is material world. Everyone is envious of the other. So Bhāgavata meant for who is no more envious. Simply loving.