Krishna says to Arjuna that "I am giving you perfect knowledge." This is our process. We receive knowledge from the perfect person. There is no use getting knowledge from imperfect person. That is useless waste of time. And who is perfect person? Who does not commit any mistake, who is never illusioned, whose senses are not imperfect, and who is not a cheater. These are the qualification. These are the symptoms of perfect person.
Lecture on Bhagavad-gita 7.2, Nairobi, , 28 October, 1975