《宋书·志·卷十四》
然而 三年不习礼制，礼制必然废毁；三年不习乐制，乐制必然崩坏 。
然 三年不为礼，礼必坏；三年不为乐，乐必崩 。
However, if rituals are not practiced for three years, they will inevitably be abolished; if music is not practiced for three years, it will inevitably collapse.