Qi Diao Kai (540 BCE-?), whose surname was Qi Diao, given name Kai, and courtesy names Zi Kai and Zi Ruo, was eleven years younger than Confucius and a native of the State of Cai. He is mentioned once in The Analects. Modest and self-respecting, he was renowned among Confucius's disciples for his virtuous conduct. According to the Records of the Grand Historian, he studied the Book of Documents (Shangshu) with Confucius but had no interest in holding office. Confucius, who advocated that "those who excel in learning should become officials," urged him to take up a post, saying, "At your age, you can now enter officialdom; otherwise, you will miss the opportunity." Qi Diao Kai replied, "I am not yet confident in the principles of governance." Confucius greatly appreciated his humility and eagerness to learn. Upright and unyielding, Qi Diao Kai upheld the principle of not compromising his countenance before others nor averting his eyes from his adversaries, embodying the virtue of "the courageous are without fear."
Qi Diao Kai (a disciple of Confucius) was highly accomplished in learning and capable of original contributions. After Confucius's death, he established a platform to teach, attracting many followers and forming the Qi Diao school within the Confucian tradition. In the 27th year of the Kaiyuan era of the Tang Dynasty (739 CE), he was posthumously honored as "Count Qi." In the second year of the Dazhong Xiangfu era of the Song Dynasty (1009 CE), he was further enfeoffed as "Marquis of Pingyu." In the ninth year of the Jiajing era of the Ming Dynasty (1530 CE), his title was changed to "Former Sage Qi Diaozi."
He developed Confucius's doctrine that "by nature, people are similar; through practice, they grow apart," arguing that some people are good by nature while others are evil, and he put forward the concepts of "Heavenly Principle" (Tianli) and "Human Desire" (Renyu), thereby forming a theory of human nature. He authored the thirteen-chapter work *Qidiaozi*.