《中庸》二十八章（依朱熹章句）論及「愚而好自用，賤而好自專，生乎今之世，反古之道，如此者，災及其身者也」，其中「反」者，歷代多作「復」解，惟揆諸其意，宜作「變」或「違」字解為是，本文試從五個方向，即本書行文、儒家思想、子思傳承、語言邏輯、時代背景等，以說明「反」用宜訓為「變」或「違」之理由，以證成清孫星衍、俞樾諸人之觀點。

　　　　　Chung Yung, chapter 28; the Master said, "let a man who is ignorant be found of using his own judgment; let a man without rank be fond of assuming a directing power to himself; let a man who is living in the present age go back to the ways of great antiquity; -on the persons of all who act thus calamities will be sure to come". In the content, the word "fan(反)", many scholars throughout the ages regarded "it" as "go back to". But if we take a close look at its content, we'd better explain it as "transform" or "go against". Thus essay is trying form five different parts, they are the contexts Confucianism, Tsze-Sze's heritage, Linguistic logic, and background of ages, to make clear the reasons why we'd better explain "fan" as "tranform" or "go against". In doing so, we also can prove Chin's great scholars, 孫星衍and俞樾's viewpoints.