本文主要是考察《易經》兩個主要的卦變義例──升降與反對，在升降義例的部分，以虞翻、朱子、李之才、吳澄為主，反對義例以俞琰為代表。虞翻承繼京房的八宮世應及荀爽的消息卦升降，建立出以六消息卦一爻主變的升降義例，然限制在於出現變例；李之才的「相生圖」在一陽一陰及三陽三陰之卦以一爻主變，在二陽二陰之卦則以二爻主變，其限制在於二陽二陰中出現一爻、二爻主變並行，故未成通例；朱子的卦變圖又擴充虞、李二子的規模，提出十消息卦的變化，使卦變結果多出一倍，其用意在充分展現卦變的所有可能，無關乎解經；反對義例主要藉著卦與卦的反卦、對卦關係解釋卦變，升降重在爻的變化，反對重在卦體變化，其限制在於未能建立通例。吳澄的卦變說將卦區分為十消息卦與六子卦所變，並依卦體的陰陽、內外結構作明確區分，整個卦變關係呈現對稱性結構，並合於完整卦變理論的三大要件：(1)具普遍涵蓋性，不容許變例；(2)卦變來源必須單一；(3)印證經傳必須相合。基於這三點理由認定吳澄的卦變說為漢魏至宋元間較為良善的卦變理論，值得重新正視。

This paper discusses the two major types of hexagram alternation principles proposed to explain the relationship between hexagrams in the I Ching: rise-and-descent and opposition. The major proponents of the rise-and-descent approach are Yü Fan, Chu Hsi, Li Chih-ts'ai, and Wu Ch'eng; the major opponent of this approach is Yü Yen. As an heir to the eight-hexagram generation-change theory of the Ching Fang school and to Hsun Shuang's rise-and-descent theory, Yü Fan proposed a six-hexagram rise-and-descent theory based on the alternation of one yao line. However, his theory has a serious limitation, in that it must admit exceptions to its general principle. Li Chih-ts'ai's Hsiang-sheng Diagram offers two ways of mapping hexagram alternation, by alternation in either one yao line or two yao lines, but his theory is unsatisfactory in that it provides no single general principle of alternation. Chu Hsi's Kua-pien Diagram is broader in scope than either Yü's or Li's theory. It models hexagram alternation by ten hexagrams and aims to offer a comprehensive account of all possibilities of alternation. In contrast to the rise-and-descent principle, which explains alternation between hexagrams through the alternation of yao lines within the hexagrams, the principle of opposition explains hexagram alternation mainly by appeal to opposition and correspondence between entire hexagrams. The limitation of this approach is that it establishes no general principle for hexagram alternation. Wu Ch'eng's theory distinguishes hexagrams into those that alternate according to a pattern of ten rise-and-descent hexagrams and those that alternate according to six descendent hexagrams. He categorizes hexagrams clearly on the basis of their yin-yang characteristics and internal and external structure. This paper proposes three criteria for a satisfactory theory of hexagram alternation and concludes that among theories proposed from the Han-Wei to the Sung-Yuan eras, Wu Ch'eng's theory best fulfills these criteria.