比興是一個本義和衍生義層疊交織而形成的觀念。唐代的比興觀，除了陳子昂、殷璠等人的論述之外，詩格中有更爲豐富的呈現；詩格之中，除了“物象比興”之外，還可見到起興、感興等議題。本文以詩格爲中心，力圖避免以後來的視角解釋古人的觀念，希望回到唐代詩格文本的脈絡，分析唐人如何看待詩歌發端之“興”、尤其是如何看待現代學者重視的原始歌謡式“起興”，又如何看待感興中的心物關係、尤其是現代學者重視的由物及心式“感興”。

The concept of bi xing(analogical and affective image)evolves with the dynamic relation between the original meaning and the derived meaning. Its development in the Tang dynasty could be examined better in Shige(Rules of Poetry), then prevailing poetic manual, than in the writings of Chen Zi’ang, Yin Fan, and others which have attracted most attention, as the former contains the discussions of different types of xing such as qi xing(image that raises the affect)and gan xing(image that stirs the affect). This article avoids explaining the early concept in terms of later usage and modern understanding. By situating the concept in its context in the Tang dynasty, the article analyzes how Tang poets viewed xing(affective image ) as the beginning of poetry, more importantly, the original balladic qi xing and the relation between heart and thing, especially the type of gan xing where the thing stirs the heart, as considerably emphasized by modern scholars.