This paper aims to look into Toegye Lee Hwang(退溪 李滉, 1501~1570)'s aspect as a teacher centerd on his letters. He used letters various ways for political, social, and academical objects, especially he made good use of the letters for educational means. The letters, corresponded with Wolchun Cho Mok(月川 趙穆, 1524~1606) who was a favorite disciple of Toegye, are the focus of this thesis.
First, the letters exchanged with Wolchun shows humanistic teaching style of Toegye. He guided his students with delicate attention, and sometimes expressed missing for his students, and worried about Wolchun because his livelihood was in danger. Second, he was a teacher who devote himself to his studies, but his attitude to his students was very modest. Thirdly, Toegye admonished Wolchun's temper sternly, at the same time advised softly. Fourth, he sincerely answered a lot of philosophical questions concerned about Neo-Confucianism (性理學) which Wolchun asked. These questions were explored in more detail, and then discussed in the next letter. Toegye deepened his philosophical point of view through lively discussion in exchanged letters with his best student Wolchun.
Toegye was not only a humanistic, open minded teacher but also he was a scholar of developing himself constantly. The letters from Toegye, especially exchanged with Wolchun shows well his character as a representative and traditional symbol of
'unity of knowledge and conduct'.