Realization relies on understanding. Understanding comes in two ways; experiential and intellectual. For true realization they must work together.
Experiential understanding comes from first-hand knowledge created through direct perception. Experiential knowledge issue forth from the fountainhead of the essence of the true Self, the bliss of God. From this bliss arises peace and love. When we begin to feel peace, we are having a direct experiential understanding of God. When we begin to feel love, we are tapping into the essence of God.
Intellectual understanding comes from a mind that studies and logically analyzes. The intellect is valuable in that it can discern what is important and unimportant, what will lead us to realization and what will keep it at bay. That type of understanding allows us to remain on the path when times are rough because we see that steps along the path will lead us to realization. Intellectual understanding allows us to realize the value of the path.
While intellectual knowledge is important, it is experiential knowledge that is paramount. We chant and feel joy. We meditate and feel calm. We repeat the mantra and feel centered. We have a direct experience. It is beyond logic, beyond the mind figuring things out. Studying the scriptures, taking courses and discussing spiritual subjects have their value, but it is the direct experiences arising from spiritual practices that open us to the essence of the true Self, Brahman, God.