宋代晁公武《郡斋读书志》卷一中曾说:“文字之学,凡有三:其一体制,谓点画有横纵、曲直之殊;其二训诂,谓称谓有古今雅俗之异;其三音韵,谓呼吸有清浊高下之不同。论体制之书,《说文》之类是也;论训诂之书,《尔雅》《方言》之类是也;论音韵之书,沈约《四声谱》及西域反切之学是也 The Song Dynasty Chao Gongwu “County vegetarian reading” Volume I once said: “The text of the study, where there are three: one of the system, that is dotted with vertical and horizontal, the difference between the song; the second exorcism, Three rhymes, that breathing has the difference of voicing .On the system of the book, ”said the text“ and the like is also; on the book of exegesis, ”Er Ya“, ”dialect“ is also; on the rhyme of the book, Shen About ”four-tone spectrum" and the Western anti-cut theory is also