Prabhupāda: You don't require to bother to say anything else. We say that Hare Kṛṣṇa mantra is sufficient for one's perfection.
George Harrison: Surely isn't it like flowers? If somebody may prefer roses and somebody may like carnations better... Isn't it really a matter for the devotee, that one person may find Hare Kṛṣṇa is more beneficial to his spiritual progress, and yet somebody else, some other mantra may be more beneficial? Isn't it like just a matter of taste? Like judging a flower. They're all flowers, but some people may like one better than the other.
Prabhupāda: But still, there is distinction. The rose flower is considered better than simply a flower without any flavor.
Yoko Ono: In that case I can't...
Prabhupāda: Just try to understand this flower example.