"...Bhakti-tattva should be accompanied with kirtana. One must accept a sadhu, guru, acarya, Vaisnava, and hear kirtana from him. Without that, no one can understand this bhakti-tattva. This is our siddhanta; one must approach a sadhu, guru, acarya, Vaisnava who is asraya-vigraha, whose only activity is hari-kirtana. He has no other activity. Without his kirtana, his sisya will never understand..."
Compiled from the lectures of His Divine Grace Srila Acarya Thakura Gour Govinda Swami.