The debate on the ”Four clues and seven Emotions” touched on here is regarded as the most important argument about Confucian philosophy in Korean Confucianism Although Yi T'oegye (李退溪) had a thorough understanding of Chu Hsi thought, but his ”doctrine of li-tao”(理到說) expressed some philosophical differences- In T'oegye's opinion, reason has its activity. The significance of T'oegye's opinion may be understood is contrast with the achievements of contemporary Cnfucianism.