The Difference Between Understanding and Realization Is Enormous

This knowing is primarily the knowing of the mind consciousness, though behind it there is also the knowing of the manas. The knowing of realization is a knowing of the nature of wisdom, different from the knowing before enlightenment. Before enlightenment, the mind consciousness speculates about the tathāgatagarbha, the manas does not know the true reality of the dharmadhātu, and takes the five aggregates as self; both consciousnesses lack wisdom. After enlightenment, the mind consciousness has realized the tathāgatagarbha, and the manas has come to know the true reality of the dharmadhātu—this wisdom is extraordinary. Afflictions will gradually fall away, ignorance will gradually diminish, grasping at self will become ever lighter, and ultimately one can transform consciousness into wisdom. Therefore, in true realization, the manas must also have realized; otherwise, the manas would lack the wisdom of realization, could not eradicate afflictions, and could not transform consciousness into wisdom. 

After enlightenment, only realization brings knowing; words cannot express it thoroughly. It is like a person who has eaten honey: only he himself knows its sweetness completely in his own mind. No matter how he describes it to others, others can merely understand it intellectually, but cannot truly and vividly experience it, because they have not tasted it themselves, not felt it themselves. Therefore, the intellectual understanding of the tathāgatagarbha speculated by the mind consciousness, and the realization of the tathāgatagarbha personally realized by the manas, differ enormously in wisdom and enormously in benefit enjoyed; the subsequent cultivation is as different as heaven and earth.