The Formation and Development of Korean Silhak, Astronomy and Geography

Gim Yuk (pen-name: Jamgok) was a reformist statesman who put innovative ideas including Daedongbeop and Siheolryeok (a calendar developed under the influence of western astronomy) into practice. Among the works left by him are Jamgok Yugo, Jamgok Byeolgo, and Jamgok Sokgo, which are collections of his prose and verse, and Yuwonchongbo (A Collection of Useful Phrases Taken from Classical Writings). Jamgok Yugo contains information on the implementation of the Daedongbeop system and the circulation of currency.

Yi Ik (pen-name: Seongho) led a group of physiocrats as the founder of Silhak during the late Joseon Period. Active in Ansan near Hanyang (present-day Seoul) in the early 18th century, he energetically absorbed the western culture and civilization that had been introduced to the capital. He stood against neo-Confucianism, which was now focused largely on maintaining the etiquette system and had been degraded to an ideological tool of the reigning powers. Yi engaged in realistically useful academic studies on history, geography, politics, economy, military, and education among other matters.

Jeong Yak-yong (1762-1836/pen-name: Dasan) was a scholar who compiled diverse relevant materials about Silhak into a single book in the late Joseon Period. He started reading the writings of Yi Ik at the age of 16 and developed a profound interest in Silhak. When he was 23, he had an opportunity to read western books obtained through Yi Beok, a brother-in-law of his brother Jeong Yak-hyeon. By 28, he had become an official and was helping King Jeongjo (r. 1776-1800) to implement a reality-based system of governance in accordance with the principles of the Silhak philosophy.

Bak Ji-won was a Silhak scholar and writer who specialized in classical Chinese in the late Joseon Period. Along with Hong Dae-yong and Bak Je-ga, Bak led a group of mercantilist scholars who sought to overcome the false social consciousness prevalent in the Joseon society, including the noble-class consciousness and the view that the Qing Dynasty should be punished for its invasion of Joseon in 1636 and its conquest of the Ming Dynasty, an ally of Joseon. They stressed the importance and usefulness of academic research to the everyday life of the grassroots people. They also pointed out that Joseon should rehabilitate her culture by accommodating more advanced cultures from China and western countries. Such a view formed the basis of the reformist and enlightenment philosophy of that period.

Distancing itself from conceptual learning, Silhak aimed to develop academic learning that would serve a practical purpose in the daily life of the people, which naturally led to the development of ‘Joseonology’ (a study of the language, history, geography, politics, economy, and culture of Joseon). This latter development brought about an epoch-making conversion from Sino-centric learning to learning focused on Joseon herself.

Choe Han-gi (pen-name: Hyegang) was a Silhak scholar and philosopher of science toward the end of the Joseon Period. He established an independent theory based on qi associated with the Confucian tradition that adopted the advanced natural science of western countries, and wrote many books displaying his interest in western academic learning. He is widely recognized as a promoter of Silhak and enlightenment philosophy at the time of a historic watershed in Joseon’s history, and as an independent scholar who strove to build a civilized society based on scientific learning.

Written by Choe Han-gi in his early days, the book examines both peaceful and turbulent periods in Korea’s history based on scriptures and historic records in an attempt to chart a way of “caring for the people according to the precepts of the scriptures,” which was the East Asian notion of economy.

This is a collection of rough drafts of writings by Choe Han-gi (pen-name: Hyegang) that was put together for the publication of a book of his works. It displays his ideas as a scholar who inherited the philosophy of leading Silhak scholars such as Jeong Yak-yong (pen-name: Dasan), developed it further, and linked it to the enlightenment philosophy. It contains forewords, selected writings, miscellaneous writings, and invocations, and serves as a basic material for studies of Choe’s ideas.

Bak Gyu-su, a grandson of Bak Ji-won (pen-name: Yeonam), was an enlightenment philosopher during the last decades of the Joseon Period. He inherited the view that Joseon should rehabilitate her culture by accommodating more advanced cultures from China and western countries, and maintained that the country should open its doors and start trading with other countries. He inherited Bak Ji-won’s mercantilism and strove to turn the country into a modern state through the opening of its ports.

He sent this letter to Yun Jong-eui (pen-name: Yeonjae) while making preparations for his trip to Yanjing, along with his attendants Gang Mun-hyeong and O Gyeong-seok, as a royal envoy in 1872 (the 6th year of the reign of King Gojong).

The letter displays his sense of expectation regarding his second trip to China, during which he witnessed the Qing people’s involvement in the modernization movement led by bureaucrats, which served to reinforce his belief about the need for aperture and enlightenment in Joseon.

Bak Gyu-su sent this letter to his elder brother in 1849 (the 15th year of King Heonjong’s reign), when he was serving as the local administrator of Yonggang-hyeon in Pyeongan-do. In the letter, he says that people were agitated about the news that an envoy of the Qing Dynasty had crossed the border, and compares the area administered by him with Hanyang based on modern scientific knowledge.

This is a portable astronomical device used to determine the positions of the stars, the time, and longitude/latitude. They were chiefly made in Arabia. This one was made by Yu Geum (1741-1788), a Silhak scholar who was well versed in geometry and astronomy, and worked together with others including Bak Ji-won who held the view that Joseon should rehabilitate her culture by accommodating more advanced cultures from China and western countries.

Astronomical devices made in Joseon under the influence of western science include the ganpyeongeui, pyeonghoneui, (Equatorial Mounting), and various astronomical maps. The pyeonghoneui (Celestial Globe) made by Bak Gyu-su (1807-1877) marks the constellations of the southern and northern hemispheres on a plane circle. The locations of the constellations tell about the time and the seasons.

The country had used the Chinese lunisolar calendar, which is based on the fact that it takes the Moon about one month to go through all its phases, and that the four seasons repeat themselves every year. This calendar has undergone frequent changes as a result of changes in the dynasty and under external influences. It was replaced by Siheolryeok under the influence of the solar calendar, which was introduced in the early 17th century.

Siheolryeok was made based on Chongzhen lishu (Chongzhen Treatise on Calendrical Astronomy) compiled by Jesuit missionaries such as Adam Shall (1591-1666) and Chinese government officials including Xu Guangqi (1562~1633) toward the end of the Ming Dynasty. It is a calendar that makes it possible to calculate the 24 divisions of the year and the times of solar and lunar eclipses.
Siheolryeok was adopted in China in 1645 during the transition from Ming to Qing, followed by Joseon in 1653. When Gim Yuk was dispatched to Beijing as a royal envoy in 1646, he instructed one of his attendants to learn about the calendar.

Siheolryeok was a new calendric system made with the aid of new astronomical devices and techniques, including theories about the universe based on the round earth theory adopted in western countries, the theory of planetary motion proposed by Ptolemy, Copernicus, and Brahe, western geometry including spherical trigonometry, celestial measuring devices (like sanghaneui, gihaneui, hosiequi) and telescopes.

Traditionally, geography had been regarded as an important subject from the political, military and everyday perspectives in Joseon. Maps were drawn up early in the country’s history, but they had limitations due to political and ethical factors, and cartographic techniques did not develop noticeably. All this changed, however, with the introduction of western maps and natural science in the early 17th century and thereafter.

In 1602, Matteo Ricci, an Italian Jesuit priest, jointly with Li Zhizao, a Chinese scholar, made Kunyu Wanguo Quantu (Chinese for Gonyeo manguk jeondo) in Beijing. The map was introduced to Joseon as early as 1603, and two hand-copied prints were made of it in Joseon at request of King Sukjong in 1708. The map currently kept at the Silhak Museum is a restored copy made in 2011 based on photos of the one that was destroyed along with Bongseonsa Temple in Namyangju during the Korean War.

The second to seventh panels are a world map. The first panel contains the foreword written by Matteo Ricci, and the last panel the foreword written by Prime Minister Choe Seok-jeong.