刘勰,六朝齐梁时文学批评家,著有《文心雕龙》,其中《丽辞》讲对偶,提出:“言对为易,事对为难;反对为优,正对为劣。”言对指不用典故的,事对指用典故的,用典故的要学问,所以认为难,不用典故,不用学问,所以认为易。反对指两句意义相反,正对指两句意义一致。正对如“鱼戏新荷动,鸟散余花落”,都讲鱼鸟的活动。又像“风定花犹落,鸟鸣山更幽”,上句静中有动,下句动中有静,两句用意不同,所以胜过两句一意了。不过还有一种正对,即两句讲两件事,用意不是相反的,两句的意义也 Liu Wei, a literary critic of Qi Liangliang in the Six Dynasties, wrote the book “Wen Xin Diao Long,” in which “Li Ci” talks about duality and puts forward: “It’s easy to be right, it’s difficult to do it right, and the objection is good and right is bad.” For those who do not use allusions, and those who use allusions to learn allusions, they think that it is difficult to do so without allusions and do not need knowledge. Opposition means that the meaning of the two sentences is opposite and that the two words are in the same meaning. It is just like “fish opera new charge, scattered birds scattered”, all talk about the activities of fish and birds. Also like “the wind is still falling, the bird song is even more quiet”. The above sentence moves quietly. The next sentence is static, and the meaning of the two sentences is different. Therefore, it is better than two sentences. However, there is another way of saying that two sentences and two things mean that the intention is not the opposite, and the meaning of the two sentences is also