《汉书·传·匡张孔马传》
我听说《六经》，是圣人用来统揽天地之心，分别善恶的标准，明晓吉凶的区分，通向人道的正路，使人不违背自己的本性的著作。
臣闻《六经》者，圣人所以统天地之心，著善恶之归，明吉凶之分，通人道之正，使不悖于其本性者也。
I heard that "Six Classics" is what saints used to control the heart of heaven and earth, differentiate the criteria of good and evil, clarify the distinction between auspiciousness and inauspiciousness, lead to the path of humanity, and prevent people from violating their own nature.