"Liezi Tangwen": "Bo Ya is good at playing the harp, and Zhong Ziqi is good at listening. Boya plays the harp, and his ambition is high in the mountains. Zhong Ziqi said: 'How good, the mountains are as tall as Mount Tai!' Zhong Ziqi said: 'How good, the mountains are like mountains and rivers!' Zhong Ziqi will definitely get what Boya wants."
Later, "high mountains and flowing water" were used to describe the rareness of a close friend or the sublime music.
Conception: