He came to Seoul when he was 23 years old to study at the National Academy, and passed the preliminary provincial Civil Service examination with top honours at the age of 33, continuing his scholarly pursuits whilst working for the Joseon government. Indeed, he continued to work for the government throughout his life, moving through 29 different positions. His integrity made him relentless as he took part in purges of corrupt government officials. In a report to the king following an inspection tour of Chungcheong Province as a royal secret inspector, he ruthlessly condemned a provincial official who, ignoring an order from an honest magistrate, busied himself in illicitly building a fortune by taking possession of government articles. On numerous occasions he was even exiled from the capital for his firm commitment to principle.
In 1549 he retired back to his home and lived there until his death. There he began to build the Dosan Seowon, a private Confucian academy offering instruction in the classics and honouring the sages with regular memorial rites. Unfortunately he died in 1570 and never lived to see the opening of his academy, although his students continued to work after his death. Dosan Seowon (or Tosan Sowon) opened in 1574, and remains in use to this day.
On his death, Yi Hwang was posthumously promoted to the highest ministerial rank, and his mortuary tablet is housed in a Confucian shrine as well as in the shrine of King Seonjo. He was the author of many books on Confucianism, and he also published a "shijo" collection, a short poetic form popular with the literati of the Choson period. During forty years of public life he served four kings (Junjong, Injong, Myeongjong and Seonjo), and his interpretation of the "li-chi" dualism gained him fame in Korea and beyond.
Toegyero -- a street in central Seoul -- is named after him, and he is depicted on the South Korean 1,000-Won note. The Taekwondo pattern Toi-Gye was named in honor of Yi Hwang.
Deaf men will not hear
And though in the noonday Heaven
The sun burns white and clear,
Blind men will not see it.
But we, thus eared and eyed,
Lack even the lame excuses
Infirmities provide.
(Translated by Graeme Wilson)