Bhakti begins there (Srila Sridhar Maharaj)

Excerpt from Awakening to the Absolute

Bhagavad gita 7.19:

          bahunam janmanam ante

          jnanavan mam prapadyate

          vasudevah sarvam iti

          sa mahatma su-durlabhah

After many births and deaths, he who is actually in knowledge surrenders unto Me, knowing Me to be the cause of all causes and all that is. Such a great soul is very rare.

So, bahunam janmanam ante… After many births, when the jnanis, those of the impersonal school, come to understand that the Prime Cause of the consciousness of their quest is a personal one, then they come to conceive of Vasudeva [Krishna as the Source-of-All-That-Is and the All-pervading Spirit/Consciousness/Light/Love].

But such jnanis are very rarely to be found. Mostly, jnanis cannot cross this line. They are lost there:

Srimad Bhagavatam 10.2.32:

            ye ‘nye’ ravindaksa vimukta-maninas

            tvayy asta-bhavad avisuddha buddhayah

            aruhya krcchrena param padam tatah

            patanty adho ‘nadrta-yusmad anghrayah

O lotus-eyed Lord, although non-devotees who accept severe penances and austerities to achieve the highest position may think themselves liberated, their intelligence remains impure. They simply speculate in various ways and do not seek the means to take shelter of You. Because they have no regard for Your lotus feet, they simply fall down from their position of imagined superiority into material existence again.

Generally, it is the fate of the jnanis to climb up to the highest position with great effort, and then, when they cannot grasp that consciousness means person — they cannot cross that understanding —, they have to revert back. They have to come back, fall back. And for those who can cross this line, who can understand that “Yes, consciousness means person — a big Personality, I am small….”, bhakti begins there. [—] The higher Entity must be dealt with with devotion.

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Commentary (Sd):

Twice in Bhagavad Gita, emphatically thus, Krishna says the same thing about the conditions for attaining Him: bhaktya tv ananyaya – ”by unalloyed devotion only”.  

In 8.22:
 
          purusah sa parah bhaktya labhyas tv ananyaya
          “The Supreme Personality of Godhead, who is greater than all,
          is attainable by unalloyed devotion only”

And again in 11.54:

          bhaktya tv ananyaya sakya
          “By unalloyed devotion only is it possible”

 
Srila Sridhar Maharaj's own translation of 11.54: 

“Although in this form of Mine I am practically impossible to be seen by all other methods, the pure devotees, by their exclusive devotion unto Me, are capable of actually knowing Me, seeing Me, and entering into My divine pastimes.”