This paper deals with the introduction of the Theory of Four Elements into Korea and Korean scholars’ reaction to it, concentrating on the time span of late 18th century and early 19th century. Two key figures are Hong Chŏng-ha(洪正河, ca. 1800), the antagonist to the theory of four elements and Chŏng Yak-chŏn(丁若銓, 1758-1816), who accepted the multi-layered earthly space system with four elements. The theory of four elements was so difficult to be accepted by Korean Confucian scholars because it contradicted traditional theories of Confucian natural philosophy, especially the theory of qi and the theory of five phases(五行說). Criticisms on the theory of four elements proposed by the Confucian scholars were mainly based on these Confucian theories of natural philosophy.
When the theory of four elements was claimed to support the Christian creationism, it appeared more fallacious to the Confucian critics, because this claimed the order of creation among four elements and it definitely contradicted the theory of five phases. Hong Chŏng-ha concentrated his criticism on this.
Even though the theory of four elements was so difficult for Korean Confucian scholars to accept, we can find several individuals who accepted this among the Confucian converts to Christianity. Chŏng Yak-chŏn made friends with these converts in his early times and, I think, it was why he could used the theory of four elements to claim his idea of rotating Earth.