《资治通鉴·魏纪·魏纪一》
现在后宫受宠的妃嫔，地位仅次于君王。如果因为宠爱她们，就立她们为皇后，使下贱的人尊贵起来，为臣恐怕今后低贱者被册立，高贵者遭废弃的事会层出不穷，没有法令制度能够限制，祸乱也就从上面开始了。 
令后宫嬖宠，常亚乘舆，若因爱登后，使贱人暴贵，臣恐后世下陵上替，开张非度，乱自上起。 
Now the favored concubines in the harem are second only to the king. If they are crowned queens because they are favored, and promoted the lowly, I am afraid that in the future, the lowly will be crowned and the noble will be abolished. There is no law to limit them, and chaos begins from the top.