Please describe the evolution process and reasons of Confucian classics in China from the Six Classics to the Thirteen Classics.

There are four original courses of Confucianism, which are compulsory courses for Confucian scholars. They are poetry, calligraphy, ceremony and music, sometimes called the Four Clubs, which are equivalent to today's literature, ancient history, politics and music classes. Later, Yihe Chunqiu was added, which was equivalent to philosophy class and modern history class at that time. This is the period of Confucius' later years, and later people call it "Six Arts" and "Six Classics".

Among them, Jing Yue was lost in the war because music was not invented in ancient times. In the Han dynasty, only the other five classics were left. Emperor Wen of the Han Dynasty began to set up a doctor of Confucian classics, and by the time of Emperor Wu of the Han Dynasty, he had completed a systematic academic institution, and the Five Classics theory has been passed down to this day.

The so-called Confucian "Thirteen Classics" in Chinese studies was said after the invention of the imperial examination in the Tang Dynasty. The aforementioned rites are divided into three rites, three biographies in the Spring and Autumn Period and nine classics. As the standard scripture in the Study of Emperor Taizong, the first nine classics have added the Classic of Filial Piety, The Analects of Confucius and Erya. Finally, in the Song Dynasty, Mencius was included in the classics, and there were thirteen kinds of * *, which were not added later, but thirteen classics were added.