He is a civil minister and outstanding scholar in the mid-term of Joseon.
His family origin is Jinbo or Jinseong and Ja is Grunghoho, Toegye, Doong, Toedo, Dosoo, Cheongryangsanin.
In 1501 (Yunsangun 7) born as the youngest son of seven sons and one daughter of Yi-sik in Ongyeri, Yean, Kyoungsangbukdo, he, when 12 years old, studied from his uncle, Yi-ho, and entered Sungkyunkwan in 1523, to become Jinsa in 1528 and passed a exam as a Eulgwa in Siknyunmungwa
He experienced the governmental position such as Bujeongja, Baksa, Hojojoarang etc. and Suchan and Jeongeon etc. in 1539, then held both positions of Hyungjojoarang and Seungmunwongyori. Performed the position of Amhaengeosa as a Geomsang, he held the several positions Gyogam and Munhak as a Sain and by way of Jangryoung to become Daesaseong next year. In the period of Eulsasahwa, he was removed from governmental official by Yi-gi in 1545 (Myeongjong enthroned), after that by way of Saboksijeong and Eunggyo etc. to became Daesaseong in 1552, Chameui of Hyungjo and Byungjo in 1554, Bujehak in 1556, Gongjochampan in 1558.
In the year of 1556, he became Gongjopanseo and Yejopahseo, in 1568 (Seonjo 1) Woochanseong and Yanggwandaejehak, and next year he retired from political world devoting himself to his study and education.
He succeeded to the Juriseol of Yi-eonjeok and insisted on Yigiyiwonron explaining the phenomenon of universe with Yi and Ki dually, though he believed Yi is more basic thing and so developed Yigiyiwonron which Juja had developed.
The core of his theory is Yigihobalseol, which suggests that 4 Dan means Yi developed first and Ki followed it and 7 Jeong means Ki developed first and Yi ride over it. The eight-year argument between him and Ki-daeseung triggered the Sachilbungiyyburon. He pursued the being and the essence of human being in the ideological aspect than physical aspect, and he believed the Pure reason is the absolute good and the best morality is what follows the absolute goods.
His scholar tradition sent down to excellent followers such as Ryoo-Seongryong, Kim-Seongil, and finally formed "YoungnamHakpa". After Injimoeran, his theory was introduced to Japan having great influence on its Confucianism.
He, by himself, established "Dosanseodang" trying to cultivate younger generation and pursue learning. He was excellent calligraphy as well as poetry, and Joongjong, Myoungjong and Seonjo respected him in sincerity. After his death, Dosanseowon was established in 1574 to become Saaekseowon in 1575. The mortuary tablet was placed in it on February 1576 and posthumous epithet "Munsun" was granted on November. And he was enshrined at dozens of Seowon including Danamseowon, Hwaamseowon and Eosanseowan through the country.
His writings are (退溪全書):修正天命圖說·聖學十圖·自省錄·朱書記疑·心經釋疑·宋季之明理學通錄·古鏡重磨方·朱子書節要·理學通錄·啓蒙傳疑·經書釋義·喪禮問答·戊辰封事·退溪書節要·四七續編》, Dosansipigok of Korean verses and Toegyepiljeok of calligraphy.