Yi Hwang
Yi Hwang was the author of many books on Confucianism. He followed the dualistic Neo-Confucianism teachings of Chu Hsi, which views "i" (Chinese "li") and "gi" (Chinese "qi") as the forces of foundation of the universe. Yi Hwang placed emphasis on the "i", the formative element, as the existential force that determines "gi". This school of thought contrasted with the school that focused on the concrete element of "gi", established by Yi Hwang's counterpart Yi I. Understanding the determinative pattern of "i" would be more essential in understanding the universe than recognizing the principles that govern individual manifestations of "gi". This approach of placing importance on the role of "i" became the core of the Yeongnam School, where Yi Hwang's legacy was carried on by prominent figures such as Yu Seong-ryong and Kim Seong-il.