Master Yung-ming Yen-shou of the Sung dynasty carried on the Hua-yen School teaching of i-hsin，Li ，and shih, and elucidated the central ideal of the unbostructedness of all shih. Both li and shih are comprised and contemplated within i-hsin. Thus, in i-hsin，all things return to one. Appearances are subordinate to mind and mind relies on appearances. The relying and the subordinate do not differ，mind and appearance are one. I-hsin actually is the powerful function and intuitive knowledge arising from the meeting of sense bases, sense objects, and consciousness. So where does the "one" return to? It is by i-hsin that one comprehends the unobstructedness of li and shih as well as the all-embracing unobstructedness of all shih, and arrives at the depths of one's mind through this illumination by wisdom. The profundity and vastness of the Buddha state are realized by "mind" and "appearances".
Yung-ming elucidated the "encompassing perfection of i-hsin" through li and shih. Li is the substance of the mind. Because substance is the still aspect it is inner，if one，and outer，if many. Shih is the function of mind. Bacause function is the moving aspect it treats the one as inner and the many as outer. Therefore，one and many，inner and outer both exist everywhere without hindrance. Through i-hsin which is the interaction of sense bases, sense objects, and consciousness, mind and appearances do not differ. The substance of i-hsin is li，its function shin. Li is therefore the nature of mind and shih its appearance. Mind comprises both nature and appearances; they co-exist without hindrance. All boundless, separate and different shih are subordinate to mind，but their superior and appearances are alike. Reduced to mind they are still and yet move，they move and，again，are still. Li and shih are identical. Li，the nature，is the melting pot where great and small encompass each other naturally and one and many penetrate each other in an instant. Thus the essence and the function of i-hsin，Li and shih are unobstructed. As they are in agreement with i-hsin，nature and appearances do not differ. All appearances are dissolved. Just like food transforms through digestion into physical strength the food of consciousness merges into mind. Interacting with i-hsin the mental appearance intuitively knows. This illuminating function of wisdom is the mental appearance of i-hsin which should be brought forth without being attacted to. Thus the shih function of mental appearance is the wisdom interacting with i-hsin. It knows everything，awakens to everything, sees everything，realizes everything，practices everything and cuts off everything. No differentiation exists therein，it is free from it, without classification and differences, virtues and spiritual attainments. It neither is nor is not，not one，not two. It knows everything to be known through not knowing，sees everything
