The scriptural quotations are sometimes contradictory, and every philosopher has a different opinion, because without putting forward a different thesis, no one can become a famous philosopher. It is therefore difficult to arrive at the right conclusion. The conclusion is, as above mentioned, to accept the judgment of authority. We follow the authority of Lord Caitanya Mahaprabhu, who is nondifferent from Krsna, and His according to Vedic scripture is that in this age this chanting is the only solution for all problems of life. And that is actually being shown by practical experience... Other quotations will not act very appreciably at this time. In a drugstore there may be many medicines, and all may be genuine, but what is required is that an experienced physician prescribe medicine for a particular patient. We cannot say in this case, "This is also medicine, and this is also medicine." No. The medicine which is effective for a particular person is the medicine for him - phalena paricyate.
Letter to Dr. Staal, 24 April, 1970