Silhak, the practical learning

Jeong Yak-yong wrote that with one pulley, 50 geun of effort lifts 100 geun, and with two, only 25 geun; his lifting device helped build Hwaseong Fortress in under three years.

After the Japanese invasions of the 1590s and the Manchu invasions of the 1600s, Joseon faced hard questions. Land registers were in disorder, farmers were poor, and the scholarly debates at court often seemed far from daily life. From the 1600s onward, a number of scholars began to write about how land, tax, trade and technology could actually be improved. Historians later grouped their work under the name silhak, usually translated as "practical learning".

Reforming the land

The first group focused on farming and land. Yu Hyeong-won, in his book Bangye surok, proposed that land be distributed more equally among those who worked it. Yi Ik, the author of the encyclopedic Seongho saseol, suggested a different approach: protect a minimum plot for each household and forbid its sale, so that no family would lose everything. Neither plan was adopted, but both show scholars looking hard at why farmers were losing their land.

Learning from Qing

The second group, often called the Northern Learning school, argued that Joseon should study the commerce and technology of Qing China, even though many Joseon scholars looked down on the Manchu dynasty. Park Ji-won travelled with a diplomatic mission in 1780 to Rehe, where the Qianlong emperor was celebrating his seventieth birthday, and wrote the Yeolha ilgi, a lively travel diary full of observations on carts, bricks, markets and roads. His friend Park Je-ga wrote Bukhagui in 1778, arguing that carts and ships were essential for moving goods and that trade would make the country richer.

Jeong Yak-yong and Hwaseong

Jeong Yak-yong, also known by his pen name Dasan, is often described as the scholar who brought these strands together. He served King Jeongjo, who reigned from 1776 to 1800 and gathered talented scholars around the royal library, the Gyujanggak. In 1792 the king put Jeong in charge of designing a new fortress at Suwon. Construction began in 1794 and finished in 1796. The wall runs 5.74 km, with four gates, firing towers and command posts, and the whole project was recorded in a detailed report that is still used for repairs today. Hwaseong was added to the UNESCO World Heritage List in 1997.

Jeong's career ended abruptly after Jeongjo died. In 1801 he was caught up in the persecution of Catholics and sent into exile, mostly at Gangjin in the far south, for about 18 years. He used the time to write. Mongmin simseo, completed in 1818, is a guide for county magistrates on how to govern fairly and protect ordinary people, and it covers everything from tax collection to famine relief. Another product of this era is the Daedong yeojido, a woodblock map of the whole country made by Kim Jeong-ho in 1861. It folds into 22 booklets that can be laid side by side to form one large map.