Public Security School: In the middle and late Ming Dynasty, the public security school headed by Yuan Hongdao was the outstanding performance of Li Zhi's literary innovation thought in the field of poetry and prose. "Sanyuan" refers to Yuan Zongdao, Yuan Hongdao and Yuan Zhongdao. Because he is a police officer in Huguang, he is called "Public Security School" and also called "Three Principles of Public Security". The core slogan of public security schools is "show your own spirit and don't stick to one pattern". They are against retro imitation and orthodoxy. Advocate a fresh and natural style with a poetic temperament. However, the followers of the public security school often make their works rough and straightforward because of their lack of literary talent.