《礼记·乐记》
从以上可知，所谓 乐 ，是由音所构成的，而其本源乃在于人心对于外界事物的感受。
乐者，音之所由生也；其本在人心之感于物也。
From the above, we can know that so-called music is composed of sounds, and its origin lies in the feelings of the human heart for external things.