(Prabhupada's lecture - Śrīmad-Bhāgavatam 1.15.49 - Los Angeles, December 26, 1973)
But that practice may be successful for one or two persons. Generally, it is not successful. But this Kṛṣṇa consciousness, bhakti-yoga system, is so easy and perfect that if you simply think of Kṛṣṇa, and if you become perfect as to think of Kṛṣṇa at the time of death, then immediately you are transferred to the Kṛṣṇaloka. Or any loka you like. Not only Kṛṣṇaloka, any loka. If you desire to go to heavenly planet, to Brahmā planet, to Satyaloka, Maharloka, Janaloka... Many thousands and millions of planets are there. Or even if you want to go beyond this material world, to the Vaikuṇṭha planet, Kṛṣṇa planet, Goloka planet, you can go there. This is the science. That is stated in the Bhagavad-gītā, yānti deva-vratā devān pitṝn yānti pitṛ-vratāḥ [Bg. 9.25]. People... Just like they are very much anxious to go to the moon planet. And what is this nonsense moon planet? It is also a material planet. Actually if you go moon planet, you can live for ten thousands of years. That is the statement in the śāstra. But after ten thousand of years you have to die.
So if you go to any planet, within this material world, the four material, I mean to say, problems, namely birth, death, old age, and disease, will follow you. You may live in one planet. Just like we are allowed to live on this planet utmost hundred years, not more than that. Or the ant is allowed to live for six hours. Or another fly is allowed one moment. There are different varieties of... Or Brahmā is allowed to live for millions of years. So according to the different types of body, we are allowed to live under certain duration of life. But nobody can be immortal here. That is not possible. That is possible when you transfer yourself to the spiritual world, Vaikuṇṭhaloka. Yad gatvā na nivartante tad dhāma paramaṁ mama [Bg. 15.6]. That is possible. So this Kṛṣṇa consciousness movement is teaching, educating people in such a way not only he goes to the spiritual world, but he goes to the highest planet of the spiritual world, Goloka Vṛndāvana, where Kṛṣṇa is there. Where Kṛṣṇa is there.