《贞观政要·卷四·尊敬师傅》
《诗经》上不是说： 要想不犯错误不忘教训，都必须从旧的规章制度入手。 
《诗》不云乎： 不愆不忘，率由旧章。 
Doesn't the Book of Poetry say: In order to avoid making mistakes and to not forget the lessons, it is all necessary to start from old rules and regulations.