Perfection requires bhakti to the all-pervading Bhagavan; theoretical realization of Brahman alone is incomplete.Listen — Srila Prabhupada Uvaca
Śrīmad-Bhāgavatam 3.25.19 — November 19, 1974, Bombay 741119SB-BOMBAY [41:19 Minutes] SB-03.25.19_741119SB-BOMBAY Nitāi: Oṁ namo bhagavate vāsudevāya. Oṁ namo bhagavate vāsudevāya. Oṁ namo bhagavate vāsudevāya. [Prabhupāda and devotees repeat] [leads chanting of verse, etc.] na yujyamānayā bhaktyā bhagavaty akhilātmani sadṛśo 'sti śivaḥ panthā yogināṁ brahma-siddhaye [SB 3.25.19] [Prabhupāda interrupts to correct Nitāi's pronunciation: "Brahma-siddhaye. Brahma-siddhaye. Brahma." Chanting of verse continues.] [break] [01:47] "Perfection in self-realization cannot be attained by any kind of yogī unless he engages in devotional service to the Supreme Personality of Godhead, because that is the only auspicious path." Prabhupāda: na yujyamānayā bhaktyā bhagavaty akhilātmani sadṛśo 'sti śivaḥ panthā yogināṁ brahma-siddhaye [SB 3.25.19] Yogī... Yogī means connecting, and brahma-siddhaye... Brahma-siddhaye means self-realization, ahaṁ brahmāsmi.
Simply to know that "I am spirit soul" is not sufficient. It must be further advanced. Then it will be siddha, perfection. Brahma-siddhaye, to realize "I am Brahman, ahaṁ brahmāsmi," that is not sufficient.
You have to make further progress. Just like to become feverless... Suppose one is suffering from fever. So medicine is given, and the no more fever—fever stop.
That is not sufficient. Not only fever should stop, but you should get strength, you should get appetite, you should have normal life. Then it is perfect cure of the disease. Similarly, brahma-siddhaye, to realize that "I am spirit soul," is not sufficient.
You have to be engaged in the spiritual activities. That is bhakti. Bhakti means spiritual activities. There is activity. It is not...
The Māyāvādī philosopher, they think that "Stop material activities." Brahma satyaṁ jagan mithyā. "Why you are engaged..." The Buddhist philosophy also, they say nirvāṇa, "Stop this material life." The Buddhist philosopher, they do not give more information. "We are suffering on account of this material combination." That is their philosophy. Because this body is nothing but combination of earth, water, fire, air, mind, intelligence and ego, so if you separate it, let the earth go to the earth, let water go to the water, let fire go to the fire, then you become zero.
If you dismantle, just like we dismantle some house, so there are so many things coming out. So let the doors be taken, somebody windows, somebody the bricks, somebody and..., rubbish somebody. Then there is no house, zero. This is called nirvāṇa theory.