What does it mean to predict day and night?

It means drinking all day.

Buzhou Buye (pinyin: bǔ zhòu bǔ yè) is an idiom, which originated from the Twenty-two Years of Zuo Zhuan and Zhuang Gong written by Zuo Qiuming in the Spring and Autumn Period.

It means drinking during the day, divining at night and not drinking at night, which is unlucky; It is often used to describe eating and drinking without restraint day and night. With derogatory meaning; Generally used as predicate and attribute in sentences.

Idiom moral:

Qi Huangong and Zhong Jing drank until late at night, hoping that someone would light a lamp and continue drinking. Zhong Jing politely suggested, "Before inviting the monarch to drink, I only predicted that everything would be fine if I drank during the day. As for what will happen if I drink it at night, I haven't divined yet and dare not be ordered to accompany me. " Later generations used divination to describe unrestrained drinking and having fun day and night. When the water is full, it will overflow, and when the moon is full, it will lose money. Once everything has passed the most powerful moment, it will begin to decline. Idioms tell people that everything should be done in moderation, knowing that enough is enough, not endlessly.