As we progress through the labyrinth of the theory behind Tai Chi & Qi Gong we encounter the term Yi, relating to the mind and how we should be using our intention generated from the mind. Initially this can be seen as a form of focus on the movement or breath; but it is helpful to know that the Chinese concept of the mind is dualistic: there is Yi (Yee) and Xin (szin). A definition from The Root Of Chinese Qigong by Jwing Ming Yang:
“Yi is the mind which is related to your wisdom and correct judgment. Yi is generated from clear thinking and is calm, peaceful, and clear. Xin is the mind which expresses your feelings, emotions, and desires. Xin can be excited, energized, and confused. When Xin and Yi work together, your inner humanity and personality will be manifested.”
The early Confucian mean of Yi 義 is right, righteousness, appropriateness but this can be intrinsically linked to zhi – will power and intention. When intent (yi 意 ) becomes permanent, we speak of will (zhi 志 ).
“Yi is the part of the mind that corresponds to judgment and therefore wisdom and it is firmed (focused) by zhi (will, see below). Xin (lit. Heart) is the emotional mind. When someone has the yi to do something it means they have commitment; when they say they have the xin to do it it means they have the desire without the commitment. When the mind and will are at one it is called yi zhi. Shen means that which is divine or spirit or immortal. It is also spirit controlled by mind (awareness plus zhi). So shen and zhi are often linked as shen zhi because a strong/firm spirit firms the will (zhi) and a firm zhi strengthens the shen.
As you can see they are all inter related – the Chinese say: yi yi hui shen, use your yi (wisdom mind) to meet your shen (spiritual mind)”
“The will (zhi 志) is commander over the qi (qi zhi shi 氣之師) while the qi is that which fills the body (ti zhi chong 體之充) . Where the will arrives there the qi halts. Hence it is said, `take hold of your will and do not abuse your qi ‘.” (Mencius II A , transl. D.C.Lau, Chinese University Press)