This idiom comes from Liezi·Yin Tang's Questions. It is recorded that during the Spring and Autumn Period， there， was a man named Yu Rui styled himself as Boya. He was very fond of learning music since his youth and followed a famous musical teacher to study music.

Once Boya wanted to translate the sound of the violent storm of the sea to music， but after thinking hard for many days， he couldn't do it well. He went to ask his teacher， Cheng Lian's advice.After due consideration， Cheng took him together to call on Cheng's own teacher， Fang Zichun.

Fang lived at an island of Penglai， but he went out when they arrived， so Cheng left Boya there and he himself went to find his own teacher outside. During the waiting time， Boya practiced the zither， climbed the mountain and enjoyed seascape everyday. Once， when Boya came back from the seaside， suddenly black clouds blotted out the sky， violent storms arose， lightening accompaniedbypeals of thunder and aheavy downpour mixed with the big waves from the sea. All kinds of sounds mingled together to be a wonderful and lofty melody.

The wonderful sight aroused Boya's enthusiasm for musical creation， he hurried to take out his zither to play with the wonderful sound at once. Afterwards， a melody of a faithful representation of the heavy downpour of the sea accomplished. Later it is known as \"high mountains and flowing waters\".

Beforelong，Boyaassociatedwithanintimate friend， Zhong Ziqi who was proficient in music. Once after Zhong enjoyed Boya's excellent music， he said with deep feeling: \"Oh， it's wouderful! I would see a vast expanse of misty， rolling waters. It's just as melodious as the flowing water.\" Before separation，they made an appointment at the same place， the same day next year. ButZhongdidn'tcomeontime. Afterinquiry everywhere， Boya found out that Zhong had died already not long before. Then Boya carried his zither to Zhong's tomb and cried bitterly. He thought， it was no use of his zither without the understanding friend， so he held it high and throw it onto a stone before Zhong's tomb and sighed mournfully: \"I broke the zither just for my understanding friend.If there is no Zhong Ziqi，who can understand my music. Even though I can meet friends every-where， it's too difficult to find an intimate and understanding friend.\"

Now we use it as a metaphor to indicate that it is too difficult to meet an understanding friend， or we use it to describe excellent music.

high mountains and flowing waters

此語出自《列子·湯問》。春秋時期，楚國郢都人姓俞名瑞，字伯牙。從小喜愛音樂，跟著名琴師成連學彈琴。

一次，伯牙想創(chuàng)作一首反映海上狂風暴雨的曲子，一連苦思冥想好幾天，也找不到動聽的旋律，便向老師成連請教。成連考慮后帶他去請教自己的老師方子春。

方子春住在蓬萊島上，成連師徒去時正巧方子春外出，所以成連把伯牙留下后自己去尋找方子春。

伯牙在等待期間，每天練琴、爬山、觀海景。

一次，伯牙從海灘回去時，突然天空烏云滿天，狂風大作，雷電交加，下起傾盆大雨，海上巨浪滾滾。頓時風聲、雷聲、雨聲、浪聲和松濤聲交織成一支雄偉而美妙的樂曲。

眼前動人的情景激發(fā)了伯牙的創(chuàng)作熱情，他急忙奔到住處，取出七弦琴，一首反映海上狂風暴雨的樂曲創(chuàng)作成功了，這就是流傳于世的《高山流水》。

后來，伯牙遇到了精通樂曲的知音鐘子期。一次，伯牙一曲彈完，鐘子期深情地說:“妙哉，這真是看見了煙波浩渺、寬廣無邊的江河流水啊!”

兩人分手時，相約一年后今天再在此相會。但到了那天，鐘子期沒有來，伯牙幾經(jīng)打聽，知道鐘子期不久前已去世。于是伯牙帶著琴到他墳前痛哭，心想知音既離他而去，再也沒有人能欣賞他的琴音了，便將琴高高舉起，狠狠地向鐘子期墳前祭臺上摔去，并高聲悲嘆:“摔碎瑤琴鳳尾寒，子期不在對誰彈，春風滿面皆朋友，欲覓知音難上難?！焙笥么说浔扔髦綦y得或用以形容樂曲的高妙。