Duality is a metaphor. Two sentences used in pairs, "the number of words should be equal, the structure and part of speech are basically the same, and the meaning is the same." This symmetrical language form has formed a neat and harmonious expression form and set off each other in content, which has a unique artistic effect. Duality refers to a special form of expression and means used in poetry creation and couplet writing. It requires that on the basis of duality, words with the same structural position in the upper and lower sentences must be "of the same part of speech and fair and opposite", and try to avoid using one word with the same structural position in the upper and lower sentences. The antithesis of metrical poems makes the language sound and rhyme harmonious, enhances the sense of rhythm and musical beauty, and achieves a high degree of perfection in expression. Therefore, the antithesis of metrical poems is very strict, and couplets that conform to the above principles are antithesis, otherwise they are not antithesis or antithesis, which is not allowed in poetry creation. Duality and duality are so different, mainly used in different styles. Because different styles have different requirements for their own expression, they also have different requirements for expression forms. As the antithesis of rhetorical methods, it is often widely used in various styles, especially in ancient Chinese prose and poems. It promotes the language, and the two even sentences complement each other and set off each other, making the language beautiful in form and expressive. Contradiction is a unique creative technique in metrical poetry. The metrical poems, which rose in Sui and Tang Dynasties, strictly require that the couplet and couplet in metrical poems must be opposed. At the same time, this method was also used in the creation of lyrics and songs, and later used in the writing of couplets. To a certain extent, antithesis can greatly improve the expressive skills and aesthetic taste of poetry, which has high artistry and expressiveness. These special functions of V are obviously beyond the reach of two forces. It can be said that "antithesis" is one of the important criteria for the creation and appreciation of metrical poetry, and naturally becomes a term exclusively for poetry. Because of this, although antithesis in metrical poems also meets the standard requirements of antithesis, in view of its own characteristics and in order to distinguish it from antithesis in general style, we usually call it antithesis rather than duality.
In short: duality: rhetoric. Use symmetrical words to enhance the effect of language. Antithesis: (rhyming, parallel prose, etc. ) antithetical sentences made according to the fluency of pronunciation and the truth of meaning. In addition to duality, duality also requires that the words with the same structural position in the upper and lower sentences of a joint sentence must be of the same part of speech, and the same words cannot be used in the same position in the upper and lower sentences. For example, "the lonely smoke in the desert falls in the long river", "where the petals have fallen like tears, the lonely birds have sung their grief" and "it is warm on the cliff of Jinsha River and cold on the crossbar of Dadu Bridge". The requirements for confrontation are extremely strict. Only the antithesis of metrical poems that meet the above principles is called antithesis, otherwise it is not antithesis or antithesis is not neat, which is absolutely not allowed in the creation of metrical poems, so it has become one of the important standards for the creation and appreciation of metrical poems.