Kuksundo practice is rooted on the Study of the Principles of Human Nature called Dan-ri-hak (단리학, 丹理學).

Dan-ri-hak is an empirical study that applies the principles of Eum-Yang and the Five Elements reflecting the natural laws of change, to the principle of human nature ; Jung-Ki-Sin (정-기-신, 精-氣-神, essence-mind & spirit-heart). This approach allows the laws of nature’s change to work directly with the life of humans.