This chapter of Gita reveals the purpose of Krsna as the cause of all causes.
arjuna uvaca
mad-anugrahaya paramam
guhyam adhyatma-samjnitam
yat tvayoktam vacas tena
moho ‘yam vigato mama
This chapter reveals Krsna as the cause of all causes. He is even the cause of the Maha-Visnu, and from Him the material universes emanate. Krsna is not an incarnation; He is the source of all incarnations. That has been completely explained in the last chapter.
Now, as far as Arjuna is concerned, he says that his illusion is over. This means that Arjuna no longer thinks of Krsna as a mere human being, as a friend of his, but as the source of everything. Arjuna is very enlightened and is glad that he has a great friend like Krsna, but now he is thinking that although he may accept Krsna as the source of everything, others may not.
So in order to establish Krsna’s divinity for all, he is requesting Krsna in this chapter to show His universal form. Actually when one sees the universal form of Krsna one becomes frightened, like Arjuna, but Krsna is so kind that after showing it He converts Himself again into His original form. Arjuna agrees to what Krsna says several times.
Krsna is speaking to him just for his benefit, and Arjuna acknowledges that all this is happening to him by Krsna’s grace. He is now convinced that Krsna is the cause of all causes and is present in everyone’s heart as the Supersoul.
One should, therefore, begin yoga practice as directed in the last verse of the Sixth Chapter. The concentration of the mind upon Krsna the Supreme is made possible by prescribed devotional service in nine different forms, of which sravanam is the first and most important. The Lord, therefore, says to Arjuna, “tat srnu,” or “Hear from Me.”
No one can be a greater authority than Krsna, and therefore by hearing from Him, one receives the greatest opportunity for progress in Krsna consciousness.
One has, therefore, to learn from Krsna directly or from a pure devotee of Krsna—and not from a nondevotee upstart, puffed up with academic education.
Therefore only by hearing from Krsna or from His devotee in Krsna consciousness can one understand the science of Krsna.