This term means a poet uses the techniques of analogy and stimulation to depict the form and the external appearance of things. He takes in internal connotations and the principles of things, thus linking originally different things and combining them. Nirong (拟容comparing appearances) attaches importance to specific forms for bixing (比兴 analogy and stimulation). While quxin (取心 grasping the essence) aims to get at the spirit and the essence of things, it therefore attaches importance to internal connotations and to the principles contained in the form of things. The combined meaning is that by giving expression to the form of things with a certain meaning, one may imply and express his thoughts and feelings. This notion appeared in The Literary Mind and the Carving of Dragons. It developed from niwu lixiang (拟物立象 create images through object imitation) in The Book of Changes. Liu Xie (465?-520) first used this term, mainly to explain that analogy and stimulation are inter-connected but are different: Analogy here means “comparing appearances.” Staying true to the principle of things is most important, and anything far-fetched should be avoided. Stimulation means “grasping the essence,” sensing the abstruse and being connected with the meaning.

When a poet uses analogy and stimulation, he comes into close contact with things and observes them thoroughly. Things may be quite disorganized, but when combined they tend to show themselves to be intimately linked. When comparing appearances to grasp the essence of things, one should be concise and resolute in forming judgment. When one incorporates various things in recitations and songs, they will swell and flow like a river. （Liu Xie: The Literary Mind and the Carving of Dragons）

Analogy means comparing the appearances of things, while association means grasping the essence of things. Meaning is what underlies the appearance. （Shi Jiaoran: Poetic Styles）