According to the Book of Rites of the Zhou Dynasty, there were activities such as "welcoming the cold on the night of the Mid Autumn Festival" and "worshipping the moon on the eve of the Autumn Equinox" during the Zhou Dynasty; In mid August of the lunar calendar, also known as the harvest of autumn grain, people hold a series of ceremonies and celebrations to thank the gods for their protection, known as the "Autumn Report". During the Mid Autumn Festival, the temperature is already cool but not cold. The sky is high and the air is cool, and the moon is clear and the sky is high. It is the best time to watch the moon. Therefore, later on, the element of offering sacrifices to the moon was gradually replaced by appreciating the moon, and the color of offering sacrifices gradually faded, while this festival activity continued and was given new meanings. During the Northern Song Dynasty, the 15th day of August was officially designated as the Mid-Autumn Festival. During the Ming and Qing Dynasties, the Mid Autumn Festival began to be as famous as the New Year's Day, becoming the second largest traditional festival in China after the Spring Festival. [17] After several transformations in thousands of years of inheritance, the spirit of "family reunion" has finally become the main cultural connotation of today's Mid-Autumn Festival.