Korean History › Early Joseon › Neo-Confucianism as state ideology
Yi I (Yulgok)
1536–1584· Person· Culture, religion & science
Well documentedSolid records, physical evidence or scientific consensus.
Leading scholar-official who argued principle and material force act as one, and pressed practical reforms.
See it on the Korean History map →What happened
Yi I (이이), pen name Yulgok, was the son of the painter and writer Sin Saimdang. Tradition says he placed first in nine state exams. He held high posts, including Minister of War (1582). Against Yi Hwang, he held that all feelings, moral or not, arise from material force (qi), with principle (li) riding on it. He wrote The Essentials of Sage Learning (1575), urged tax and military reform, and tried to mediate between the new Easterner and Westerner factions.
Why it matters
His Giho school near Seoul became the intellectual core of the Westerner faction that dominated later Joseon; he and his mother are on the 5,000- and 50,000-won notes.
Legacy and how we know
His collected works (Yulgok jeonseo), memorials recorded in the Sillok, and Ojukheon, his birthplace house in Gangneung.
Still debated
Whether he truly proposed training a 100,000-man army before the Imjin War is debated; see that link.
Connections (2)
▸Yi I (Yulgok) challenged the views of Yi Hwang (Toegye)Well documented
The connection
Yi I visited the elder Yi Hwang in 1558 and admired him, but later rejected his answer to the Four-Seven question. Toegye said moral impulses issue from principle (li); Yulgok argued that only material force (qi) acts, with principle riding on it. Their followers became rival schools, Yeongnam and Giho, tied to different factions.
When and how
A 1558 visit to Yi Hwang's home near Andong; Yi I's main critique came in his 1572 letters with Seong Hon, after Yi Hwang's death in 1570.
How we know
Their letters and essays survive in both men's collected works.
Debates and open questions
How far the philosophical split drove factional rivalry, rather than serving as a banner for it, is debated.
▸Yi I (Yulgok) warned of military weakness before Imjin War (Japanese invasions of Korea)Debated
The connection
Yi I warned repeatedly that Joseon's army and finances were hollow. Tradition says that in 1583 he urged training 100,000 soldiers against a coming crisis and was ignored, nine years before Japan invaded. If true, it made him a prophet of the disaster.
When and how
About 1582–1583 in Hanyang (Seoul), while Yi I served as Minister of War under King Seonjo.
How sure are we?
His reform memorials are genuine, but the 100,000-man plan appears only in his disciples' writings and the Westerner-revised annals, not the original Seonjo sillok.
Debates and open questions
Many historians think followers added the 100,000-army story to glorify him; others accept it. Either way, he did not predict Japan specifically.