This paper is a preliminary study which challenges the dominant view of
Sirhak during last 80 years. Sirhak has been viewed as a modern thought by
most of the historians who made effort to discover a modern factor at
philosophical, political and economical aspect in the late period of Chosun. In
this article, the author focuses on the concept of 'Silsim'(實心) in Yulgok which
makes a pair whit Silli(實理). In Yulgok's philosophy, Silli means a kind of
principle which makes universe unceasing, and Silsim refers to a practical will
which can realize such principle at everyday life. Yulgok thought change is an
essential character of universe, and so political innovation is needed when
society changes. And Silsim makes it possible to do moral practice and
institutional reform.
Silsim of Yulgok, on one hand, succeeds 'Seong'(誠=sincerity) which was
considered as an important religious and moral attitude from early period of
Chosun, and on the other hand interprets it as Sil(實=practice). Later, Yi
Sugwang uses a phrase of "doing practical politics(Siljeong) with practical
mind(Silsim), and this phrase was used by many thinkers in the late period
Chosun. He also succeeds Teogye's thought of 'reverence on Heaven' which
interprets Li in the philosophy of Zhuxi as religious Heaven.
Yulgok is similar with Wang Yangming in that he pays emphasis on
'practice'(行), but different with Wang Yangming in that he thought, like Chu
Hsi, mind does not exist independently with Li. Yulgok's concept of Silhak as
a practical learning has its root in his view of learning, and we can find
similar concepts in later period, for example 'haengsa'(行事) in Dasan‘s
philosophy or ‘learning’(學) in Eastern Learning(學).