In the Book of Changes, there is a saying that there are six yin and nine yang, and two and nine are heavy, which is called Chongyang and nine. There is a folk custom of climbing on that day, also known as "Climbing Festival". There are also sayings such as Double Ninth Festival, cornus and Chrysanthemum Festival. The homonym "Jiujiu" means "for a long time", which is often used to worship ancestors and carry out activities to respect the elderly on this day.