A great scholar of the mid-Joseon period who embraced and carried on the learning of both Toegye and Nammyeong; art name Hangang (寒岡)
| Life | 1543 ~ 1620 |
| Era | 조선 |
| Clan | 청주 정씨 |
Jeong Gu, known by the pen name Hangang, was born in Seongju, North Gyeongsang Province. He studied Neo-Confucianism under both Yi Hwang (Toegye) and Jo Sik (Nammyeong), uniting the two great intellectual lineages of the Yeongnam school, and was versed not only in classical learning but also in ritual studies, history, medicine, and calligraphy.
Entering government service in 1573, he served as magistrate of numerous counties, including Changnyeong, Dongbok, Tongcheon, Seongcheon, Cheongju, Hongju, Gwangju, and Andong, as well as governor of Gangwon Province, and raised righteous army volunteers as magistrate of Tongcheon during the Japanese invasions. In ritual studies he proposed that the rites of kings differ from those of scholar-officials, and he compiled local gazetteers and medical texts. In 1603, when Jeong In-hong rejected Yi Hwang and Yi Eon-jeok while editing Nammyeong's collected works, Jeong Gu's attempt to persuade him failed, ending their friendship.
He trained over three hundred disciples, including Heo Mok and Yun Hyu, becoming the wellspring of the Geun-gi Namin school of the late Joseon period. He left behind more than fifty works, including Oseonsaengyeseolbullyu, Simgyeongbalhwi, and Hangangjip, and was enshrined at more than ten Confucian academies nationwide, including Hoeyeon, Cheongok, and Dodong Seowon. He received the posthumous title Munmok.