“The position of the mind or heart in the human body is similar to that of the king within a nation, and the nine orifices in the human body function in the same way as officials do at court.” Ears and eyes are for seeing and listening. When the mind does not intervene, the ears and eyes play their roles as they should. If however the mind is beset with desire, the eyes may fail to see what lies before them, and the ears may fail to hear what passes by. In the same way, “when those in superior positions act against the principles they are supposed to abide by, those in lower positions will hardly function as they are supposed to.” Therefore, doing nothing to hinder the operation of the nine human orifices is the art of the mind, which explains why it can be likened to a king. (Guanzi)

People have aspirations and mental alert in their nature, but the emotions of sorrow, joy, happiness and anger are not manifested in a stable manner, and react to external stimulation. That is what gives away their inner thought. (The Book of Rites)