Prabhupāda: One perfect person is sufficient to teach thousands of imperfect persons.
Professor (Hṛdayānanda): He says he thinks you are right because the example is Buddha and Christ, and so many people follow them.
Prabhupāda: They are perfect, but the followers do not follow the instructions. That does not mean they are imperfect.
Professor (Hṛdayānanda): He says that it is not enough, contact with a perfect being, because, as you said, so many people come into contact but change teachings. Therefore it's necessary also to realize the knowledge.
Prabhupāda: Therefore you have to keep the original teaching in perfect order, without any interpretation.