Having theories thoroughly mastered in the mind does not equal having actual realization

Any theory, once you have understood it, comprehended it, grasped it, and know how to apply it—able to answer questions fluently, able to explain it to others, able to explain it clearly, with everything crystal clear in your mind—

yet, does that amount to having realized it through actual practice? Does it amount to being your own theory, your own view, your own insight?

Reaching the point where a theory is thoroughly mastered in the mind is not difficult; answering fluently and drawing inferences from one instance to others is not difficult either. What is difficult is being able to advance to the stage of seeking verification, realizing it step by step through actual practice. And what is most difficult is being able to pass smoothly through the stage of actual practice and truly attain realization.