两仪
Two Modes

事物生成与存在的两种仪则，是用以表现“八卦”生成过程的一个易学概念。《周易·系辞上》言：“易有太极，是生两仪，两仪生四象，四象生八 卦。”“太极”分化而形成相互匹配、对立的两面，即是“两仪”。就“两仪” 的具体内容而言，古人有不同的理解：其一，从宇宙生成的角度来看，“两 仪”或指天、地，或指阴、阳。其二，从占筮的角度来理解，“两仪”指由 四十九根蓍草任意划分出的两组，或指画卦中分出的奇偶两画。
Things come into being and exist in two modes, which are used to describe how the eight trigrams are formed. As explained in The Book of Changes: “Changes involve taiji (太极 the supreme ultimate), which produces two modes. The two modes generate the four images, and the four images give birth to the eight trigrams.” Taiji divides itself into two mutually complementary but opposite parts, or modes. Ancient Chinese had different views as to what the modes represented. Some believed that from the point of view of the formation of the universe, the two modes could be understood as heaven and earth or as yin and yang. Others thought that as a term in divination, the two modes could refer to two groups formed by randomly dividing up 49 yarrow stalks used in divination, or the two lines, solid or broken, in the hexagrams of The Book of Changes.

引例 CITATIONS

混元既分 ，即有天地 ，故曰 “太极生两仪 ”。 （《周易 •·系辞上》孔颖 达正义） （混一的元气既已分化，即形成了天与地，所以《周易》称“太极生两仪”。）
Once the primordial chaos divided itself, there came into being heaven and earth. Therefore it is said in The Book of Changes that taiji (the supreme ultimate) gives birth to the two modes. (Kong Yingda: Correct Meaning of The Book of Changes)
分阴分阳，两仪立焉。 （周敦颐《太极图说》） （分化出了阴与阳，两仪就确立了。）
When yin and yang appeared, the two modes emerged. (Zhou Dunyi: The TaijiDiagram Explained)