Summer Solstice idiom
In Chinese, an idiom "杯弓蛇影" is related to Summer Solstice
According to the records of Fengsutong (a book about Chinese customs), written by Ying Shao from the Eastern Han Dynasty (AD25-220), a man named Du Xuan attended a banquet on Summer Solstice, where he mistook the shadow of a bow in his cup for a snake and he had to drink it out of fear.
After the banquet, he felt chest pains and a bellyache and couldn't recover even after seeing many doctors. Finally, he found he had mistaken the shadow of a red crossbow on the wall for a snake in his cup and recovered. Later, people used this idiom to refer to people who are suspicious and frighten themselves.
