If you purchase Bhagavad-gita, you purchase Bible, you purchase Koran, or..., there are so many literatures. They are also authorized. That's all right. But you cannot learn them by your own study. Tad-vijnanartham sa gurum evabhigacchet [MU 1.2.12]. One must go and learn it from the spiritual master; exactly you purchase some scientific book, medical science, or engineering and study at home. Oh, you will never be acknowledged as a medical practitioner. You have to admit yourself into the, that disciplic succession, medical college. You have to attend lectures. Then, when you pass degree, then you will be admitted.
Lecture on Bhagavad-Gita 9.26-27, New York, 16 December, 1966