In this article, I am going to give a preliminary observation on Korean mathematical texts in the second half of the 19th century. I will focus on Nam Byung Gil's (1820-1869) Vu Yi He (A Study of commentaries on ”Tian Yuan Shu”, 1855). It is a text basically devoted to a critical evaluation of Chinese mathematician Li Rui's (1768-1817) restoration of the tradition ”Tian Yuan Shu” in terms of the Western ”Jie Gen Fang”. Apparently based on the adaptation that Li Rui, among others, made of the Cardano's version of Western algebra, Nam Byung Gil, who knew Chinese mathematics well, was able to react in a ”meta-cognitive” manner. Specifically, he commented on commentaries. His experience of studying the discipline is very interesting and illuminating, especially for teaching learners of introductory algebra.