《文心雕龙·诸子》
无论它们阐述道理或议论政事，都是从经书发展下来的；其中内容纯正的，便符合于经书的规则；内容杂乱的，便违背经书的法度。《礼记》中的《月令》，是采用《吕氏春秋》的《十二纪》；而《礼记·三年问》的内容，也写进了《荀子》中的《礼论》。这些都是内容纯正的例子。
其纯粹者入矩，踳驳者出规。《礼记·月令》，取乎吕氏之纪；三年问丧，写乎《荀子》之书：此纯粹之类也。
Whether they explain principles or discuss affairs of government, they have all developed from the Classics; those with a pure content are in accord with the rules of the Classics; those with a mixed content violate the canons of the Classics. The <Monthly Orders> in the <Book of Ritual>, adopted the <Twelve Periods> in the <Spring and Autumn of the Lu Clan>; and the content of the <Three-Year Questions> in the <Book of Ritual> was also included in the <Treatise on Ritual> in the <Xunzi>. These are examples of pure content.