Disciple of Yi Hwang, scholar from Andong; pen name Jiheon; joined volunteer forces in the Japanese invasions
| Era | 조선 중기 |
| Clan | 청주 정씨 |
Jeong Sa-seong (鄭士誠) was a mid-Joseon scholar from Andong, seat Cheongju, courtesy name Jamyeong, pen name Jiheon (芝軒). His father was the Saseomsi official Jeong Du and his mother was a daughter of Gwon Sik of the Andong Gwon; his younger brother was the official Jeong Sa-sin. His dates were not confirmed here.
He studied under Kim Eon-gi at seven, under Gu Bong-ryeong at ten, and entered Yi Hwang's school in 1561. He passed the licentiate exam in 1568, was appointed a tomb keeper in 1587, resigned in 1589 and returned home, then in 1591 served again as shrine keeper and the Naja office before becoming magistrate of Yanggu. He soon returned home to study.
In 1596 he wrote Yeokhak gyemong jirui, and the next year joined Gwak Jae-u in volunteer service at Hwawangsan Fortress in Changnyeong. He was enshrined at Okgye Seowon in 1731 (later removed) and at Hagam-ri shrine in 1779. His works include the Jiheon munjip and Yeokhak gyemong jirui.
After several teachers in his youth, Jeong Sa-seong entered Yi Hwang's school in 1561, which is understood as the point at which the Seolheon line settled in Andong linked to the Toegye school. His name survives as one of Yi Hwang's disciples who devoted himself to learning in the provinces.
He did not stay long in office and valued study. In 1596 he wrote Yeokhak gyemong jirui, organizing questions on Zhu Xi's Introduction to the Study of the Changes, and in 1597 took part in volunteer service with Gwak Jae-u at Hwawangsan Fortress in Changnyeong, a defense well known in the story of Joseon's volunteer armies.
He was enshrined at Okgye Seowon in 1731 and later removed, then enshrined again at the Hagam-ri shrine in 1779. His case reflects how late-Joseon enshrinement shifted with politics. His younger brother Jeong Sa-sin passed the civil examination and served as judge of the Slave Bureau and magistrate of Miryang.
The location of his grave was not confirmed.