“因声求义”是清儒在训诂研究中倡导的方法,一般有两个预设:一是“因声求义”之“声”限于古音,二是所求之义一般为实词词义。虚词没有实在的词汇意义,但探索虚词由来的途径,同样可以运用“因声求义”的方法。从发展角度看,这是“因声求义”;从虚词溯源角度看,可称之为“因声探源”。“因声探源”有不同的途径:1.某个实词由实到虚的语法化途径;2.求证某个虚词由古字变为今字的缘由;3.求证后代两个不同的语法成分有一个共同的来源。4.求证后出的语法成分与两个不同来源的词相关联。 “Seeking justice due to sound” is a method advocated by Confucianism in the study of exegesis and mutilation. There are generally two presuppositions: one is “the sound of sound”, the sound of sound is restricted to the ancient sound, and the other is the one sought Meaning is generally meaning words. Function words do not have a real meaning of the word, but the way to explore the origin of function words, the same can be used “sound because of sound ” approach. From the development point of view, this is “sound because of sound ”; from the perspective of function words can be called “because of sound source ”. “There are different ways because of the sound source ”: 1. A real word from the real to the virtual grammaticalization; 2. To verify the reason why a function word has changed from the ancient word to the present word; 3. Verify that the two generations are different The grammatical components have a common source. 4. After verification, the grammatical composition is related to two words of different origins.