By His Divine Grace A.C.B. Swami Prabhupada
If one wants standard transcendental knowledge, not upstart knowledge, one must received it from the parampara system, the disciplic succession. Another meaning of the word srotriyam mentioned above is "one who has heard from a guru in the disciplic succession." And the result of this hearing will be brahma-nistham, "He is firmly fixed in the service of the Supreme Personality of Godhead." He has no other business. These are the two main qualifications of a bona fide guru. He does not need to be a very learned scholar with an M.A., B.A., or Ph.D. No. He simply needs to have heard from the authority in disciplic succession and be fixed in devotional service. This is our system.