He was deeply interested in studying astronomy, geography, history, literature, culture, religion, paintings, calligraphy, and customs while remaining out of public office.
When King Jeongjo opened the Kyujanggak, he appointed well-known scholars whose duties were to compile, proofread and transcribe books, such as Geomseogwan (檢書官).
Yi Deokmu was called the Four Geomseo along with Yu Deuk-gong (유득공; 柳得恭), Bak Jega (박제가; 朴齊家) and Seo Isu (서이수; 徐理修).
[1] The late Joseon dynasty, during which Yi Gyu-gyeong lived, saw the development of commerce and handicrafts as the agricultural productivity increased.
The boundaries of society-led industries started expanding in all areas, and society posed the need to transition the recognition standard of the subjects who recognize social issues.
He tried to recognize objects and issues accurately and firmly in many ways[2] Yi inherited numerous books and reading notes accumulated by his grandfather and father.
This focused on the compiling of practical books rather than on the traditional Confusianism, and gathered the knowledge of those days in encyclopedia style.
[4] The new knowledge and innovative ideas that Yi suggested so that they could be widely communicated to objects of all ages and countries seem to have been seriously and desperately accepted by early enlightenment leaders.