Devotional service entails being initiated by a bona fide spiritual master and following his instruction in regard to hearing about the Lord. Such a bona fide spiritual master is accepted by regularly hearing from him about the Lord. The improvement in knowledge and detachment can be perceived by devotees as an actual experience. Lord Śrī Caitanya Mahāprabhu strongly recommended this process of hearing from a bona fide devotee, and by following this process one can achieve the highest result, conquering all other methods.
Reference:- SB 3.5.42
