Why did the ancients use bamboo silk as a metaphor for music (classical Chinese)

There is no hurry, no tedious work.

Sixian orchestral music has existed in China since ancient times. And spread it widely.

Like erhu, guzheng and pipa, they all belong to the silk string.

Flute. Xiao. Waiting belongs to orchestra.

These are probably related to the traditional culture since ancient times.