《淮南子·览冥训》
这说明人如果有悲惨经历就会在内心精神世界形成悲情，以后一旦触境生情就会在言语和歌声中流露出来，并引起有同类经历人的共鸣；因为这种悲惨经历、悲切感情都是每个个人的自身体验，所以是无法传授给人家的；同样无这种悲惨经历的人是无法向人学会这种悲切感情的。
精神形于内而外谕哀于人心，此不传之道。使俗人不得其君形者而效其容，必为人笑。
This shows that if people have tragic experiences, they will form sadness in their inner spiritual world. Once they touch the scene in the future, they will show it in their words and singing, and resonate with people who have similar experiences; because this tragic experience and sad feeling are each individual’s personal experience, so it is impossible to teach others; similarly, people who have not had such a tragic experience cannot learn this sad feeling from others.