Srimad Bhagvatam: SIMPLY BY EXECUTING DEVOTIONAL SERVICE ONE CAN BECOME FULL OF ALL KNOWLEDGE.
TRANSLATION
NARAYANA, THE SUPREME PERSONALITY OF GODHEAD, WHO IS FULL OF ALL OPULENCES, IS PREDOMINANT WITHIN THE CORE OF YOUR HEART BECAUSE OF YOUR BEING A PURE DEVOTEE. HE ALWAYS DRIVES AWAY ALL THE DARKNESS OF IGNORANCE, AS THE SUN DRIVES AWAY THE DARKNESS OF THE UNIVERSE.
PURPORT
THE WORDS BHAKTYA KEVALAYA INDICATE THAT SIMPLY BY EXECUTING DEVOTIONAL SERVICE ONE CAN BECOME FULL OF ALL KNOWLEDGE.
Krshna is the master of all knowledge (aisvaryasya samagrasya viryasya yasasam sriyam).
THE LORD IS SITUATED IN EVERYONE'S HEART (isvaram sarva-bhütanam hrd-dese 'rjuna tishthati), AND WHEN THE LORD IS PLEASED WITH A DEVOTEE, THE LORD INSTRUCTS HIM.
ONLY TO THE DEVOTEES, HOWEVER, DOES THE LORD GIVE INSTRUCTIONS BY WHICH TO ADVANCE FURTHER AND FURTHER IN DEVOTIONAL SERVICE.
TO OTHERS, THE NONDEVOTEES, THE LORD GIVES INSTRUCTIONS ACCORDING TO THE MANNER OF THEIR SURRENDER.
The pure devotee is described by the words bhaktya kevalaya.
Srila Visvanatha Chakravarti Thakura explains that BHAKTYA KEVALAYA MEANS JNANA-KARMADY-AMISRAYA, "UNMIXED WITH FRUITIVE ACTIVITIES OR SPECULATIVE KNOWLEDGE.”
SIMPLY SURRENDERING AT THE LOTUS FEET IS THE CAUSE OF ALL A DEVOTEE'S ENLIGHTENMENT AND AWARENESS.