조선 후기 과학 사상가인 담헌 홍대용의 시문집이다. 이 책에 수록된 「의산문답醫山問答」은 1765년(영조 41) 북경 연행燕行 경험을 바탕으로 지은 소설로, 유학 공부를 끝낸 허자虛子가 숨어 살던 실옹實翁을 만나는 이야기다. 소설에서 ‘지구는 둥글고, 스스로 돌며, 우주가 무한하다’는 등 당시로서는 새로운 깨달음을 펴 나간다. 당대 전통적 학문의 헛됨을 암시하고, 청과 서양의 선진 문물을 적극적으로 수용하려 했던 홍대용의 사상이 잘 드러난다. 여러모로 급진적 내용을 담고 있는 『담헌서』는 1939년에 이르러서야 연활자鉛活字로 간행되었다.

This is a collection of poetry and prose by Hong Dae-yong (pen name Damheon), a scientific thinker of the late Joseon era. “Dialogue on Mount Uisan,” which is included in this book, is a short story he wrote based on his journey to Beijing in 1765 (the 41st year of King Yeongjo’s reign). The story revolves around Heoja (lit. Master of Void), who has finished his study of Confucianism, and Sirong (lit. Old Man of Practicality), who has sequestered himself. Within the narrative, Hong reveals groundbreaking realizations influenced by Western Learning, including the earth’s roundness, its rotation, and the concept of an infinite universe. The story hints at the futility of traditional scholarship of the time and showcases his openness to embracing the advanced cultures of the Qing and the West. Radical in many ways, it was not until 1939 that Damheonseo was published in lead movable type.