 On the front of self-cultivation, Yulgok proposes a model of Integrity (sŏng 誠) for achieving sagehood (Ro 1989). Integrity is the foundation of self-cultivation because it enables one to nourish one’s own Vital Force, and the heart/mind can be made the master of one’s body and the commander of human nature and feelings through its agency. But Integrity as the source of transforming Vital Force within us does its works exactly because it is the real principle of heaven and the original essence of the mind/heart. The heart/mind then originally possesses Integrity as its inherent moral quality.