Idiom, why is it quiet at night?

Idiom, what kind of night is quiet:

It is late at night and people are quiet,

It is late at night and people are quiet

It is late at night and people are quiet Definition:

Night is quiet: The night is coming to an end. In the dead of night.

The night is quiet_Baidu Chinese

[Pinyin] [yè lán rén jìng]

[Source] A three-fold copy of "The Romance of the West Chamber" by Wang Shifu of the Yuan Dynasty: "There is a The sun willows cover the flowers; the mist blocks the clouds; the night is quiet; the people swear each other.