Jia Yi (20 BC1-168), a native of Luoyang (now northeast of Luoyang in central China), was a famous political commentator and thinker in the Western Han Dynasty. At the age of eighteen, he was famous for reciting poems. At the beginning of Emperor Wendi's accession to the throne, Jia Yi, who was only in his twenties, became a doctor with the strong recommendation of Wu Gong, the youngest of all doctors. Because he showed outstanding performance every time he discussed the imperial edict, he was finally promoted to be a loyal doctor.

Jia Yi has many original views on the country's major policies. He believes that since the establishment of the Han Dynasty for more than 20 years, the society has been basically stable, so we should rectify the new moon, change the colors, clarify the official names, advocate rites and music, and amend the new law. Emperor Wen attaches great importance to Jia Yi and intends to let him hold public office. However, due to the opposition of Zhou Bo, Guan Ying and others, Wendi had to let Jia Yi be the teacher of Changsha King first. Later, Jia Yi wrote "Bird Fu" in Changsha, using a bird to express his anguish and sadness. Emperor Wen later summoned and asked ghosts and gods. Since then, Jia Yi has served as the teacher of Liang Huaiwang, and has repeatedly stated the strategy of governing the country to Emperor Wen. These expressions are called "public security policy" by later generations. In the eleventh year of Emperor Wendi, that is, BC 169, King Huai of Liang accidentally fell off his horse and died. Jia Yi was very sad and blamed herself. He felt that he had not taken good care of King Huai Liang. A year later, he died of grief at the age of 33.

Later generations compiled Jia Yi's works into Xin Yu, and achieved great ideological and theoretical achievements. He learns from others' strengths and has original ideas. His political thoughts and ideas are embodied in Public Security Policy and Guo Qin Theory.

In On Qin, Jia Yi comprehensively discussed the painful lessons of the rapid death of the Qin Dynasty. He believes that the reason why Qin annexed the six countries to achieve reunification is the use of "deception." After reunification, he believed that Qin should change its ruling style in time. However, Qin still carried out the harsh legal system advocated by legalists and imposed heavy penalties on minor crimes, which eventually led to intensified contradictions and short-term extinction. "Public Security Policy" is a comprehensive and profound analysis of the dark side of society, and then provides more targeted countermeasures, including reducing the overall strength of multiple governors, paying attention to ethics, and using penalties with caution. In his view, the long-term stability of feudal rule depends on the rulers' attention to agriculture and the enthusiasm of farmers. He also advocated the establishment of a hierarchical system, safeguarding the dignity of the monarch and making the family closely United. We should also pay equal attention to morality and punishment, and at the same time advocate rites and music and educate the people in morality. In view of the actual situation of the confrontation between the governors and the central government at that time, Jia Yi advocated trying to limit it as soon as possible. The specific measures were to seal more governors and disperse forces. Later, Wendi also adopted his suggestion.

Jia Yi's prose level is also very high, and he is recognized as an ancient prose writer. His political essays were sharp and fluent, and he was praised by Mr. Lu Xun.