文主要分析「勢」概念在漢、唐、宋、明等朝代的義涵發展，而以賈誼、柳宗元、朱熹、陸九淵、王夫之等人以「勢」論國家施政及歷史演變爲探討主題。賈誼以「勢」檢討漢帝國外交政策及秦帝國興衰，開創了以「勢」思考朝政措施及歷史發展的新境界。而賈誼所創的r事勢」「理勢」之新詞，也打開了宋明理學家論史時的新思路，肯定了「人」在「勢」中的價値判斷。如果從「勢」概念所特有的「相對關係」之思考的角度上來看，則以「勢」論國家施政，擴大了「勢」義涵的相對空間廣度：則以 「勢」論歷史發展，則開鑿了「勢」義涵的時間縱深：而「價値判斷j在「勢」概念中的突出，更顯示了「勢」義涵的人文意義。

This article attempts at an analysis of the development of the notion of shih in Han, T’ang，Sung and Ming times. Focus our discussion has been placed upon the notion of shih as a force of statecraft and evolution of history in the thought as Chia Yi, Liu Tsung-ylian, Chu Hsi，Lu Chiu- yiian and Wang Fu-chih. Chia Yi of Western Han analyzes Han’s diplomatic policy and the vicissitude of the Ch’in Dynasty in terms of the notion of shih. Chia Yi opens up the floodgate of shih as a new percept in considering imperial policy and historical development such new terms as “propensity of things” and “tendency of principle” as coined by Chia Yi inspired the Confucianists’ thinking on the place of man in “propensity” in Sung-Ming Neo-Confucianism. In sum, this article suggests that the application of shih in statecraft enlarges the spatial width of the notion of shih on the one hand. On the other，the explaining of history in terms of shih enhances the temporal dimension of the definition of shih. Moreover, the fact that the notion of shih is very much value-charged reveals the profound humanistic implications of the notion of shih.