《孔子家语·辩乐解》
古代贤明的君王制作音乐，奏中正无邪的声调加以节制，向南方流传，不流向北方。
夫先王之制音也，奏中声以为节，入于南，不归于北。
The wise kings of ancient times created music, using it to restrain and regulate the sound of zheng and wu, spreading it southwards but not northwards.