Srila Gour Govinda Swami would say..

Krishna says, ” Think of me become my devotee ” at the end of the Gita
But He didn’t say how in detail and depth .
So He came again as Sri Caitanya Mahāprabhu to practically teach how by example, by teaching about the love of the residents of Vrndavana, who in love spontaneously thought of Krishna
And The Goswami’ s who were taught by Mahāprabhu greatly expanded the tenth Canto of Srimad Bhagavatam with descriptions of Radha Krishna Nitya lila , Sri Caitanya Mahāprabhu would meditate on the works of many other writers of the Love of the residents of Vraj . The Goswami also, along with analysing the purificatory process of Bhakti, from Karma and Niskarma karma yoga , leading to buddhi yoga or jnana yoga to its perfection, Bhakti yoga in spontaneous love . Sri Caitanya Mahaprabhu adds Bhakti yoga immediately by chanting Hare Krishna under the direction of Sri Guru, which connects to and is purifying the other types of yoga .
So seems like a kind of ” new testament “and new process has come about , and the Bhagavad Gita is the excellent summary study of everything , but we require The Sri Caitanya Mahāprabhu connection along with the Goswami’s and Sri Guru who follows Rupa Ragganatha..and those that are their followers.
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