Bhagavad Gita, Chapter 13, Verse 19

Thus Kshetra, knowledge, and that which has to be known, have been briefly stated. Knowing this, My devotee is fitted for My state.

Understanding this teaching for real is tied here directly to devotion, not intellectual effort alone.

Krishna states plainly that his devotees are the ones who genuinely grasp what's just been explained. Real comprehension, once again, is shown running through devotion rather than around it.