Who Is on the 5,000 Won Note? Yi I (Yulgok), Joseon's Practical Philosopher

The man on South Korea's 5,000 won note is Yi I (1536–1584), better known by his pen name Yulgok, a philosopher, writer and Confucian scholar who also served as a high-ranking official of the Joseon dynasty. His portrait has been used on the 5,000 won note since 1972. He is remembered as one of the two great minds of Korean Neo-Confucianism, alongside Yi Hwang, who appears on the 1,000 won note, and as a scholar who believed learning should be used to fix real problems in government.

A quick guide to his world

The Joseon dynasty ruled Korea from 1392 to 1910. Its official philosophy was Neo-Confucianism, a school of Confucian thought that tried to explain both the moral nature of human beings and the structure of the universe. Officials were chosen through demanding civil service examinations on the Confucian classics, so a brilliant scholar could rise to the top of the state.

Yi I was born in Gangneung, on Korea's east coast, into the Deoksu Yi clan. He was born at Ojukheon, his mother's family home, the third son of Yi Won-su and Shin Saimdang. His mother was an accomplished artist and calligrapher, and she now appears on the 50,000 won note, which makes them the mother and son of Korean money.

His art name, Yulgok, means "chestnut valley".

A child prodigy and a crisis

Yi I is said to have finished the Confucian classics by the age of seven and passed the civil service literary examination at 13. Then his life changed. His mother died when he was 16. After mourning her, he spent time at Mount Kumgang studying Buddhism, and he left at 20 to devote himself to Neo-Confucianism.

This Buddhist period mattered later. In a Confucian state, his political opponents used it as a reason to attack him.

Nine times first place

Yi I is famous for his examination results. He won top honours in the civil examinations nine times, which earned him the nickname Gudo Jangwon-gong, roughly "the man who came first nine times". His essay Cheondochaek ("A Treatise on the Way of Heaven") helped make his reputation.

In 1558 the young scholar visited the older philosopher Yi Hwang at Dosan. The two men discussed learning for two days; Yi Hwang admired his talent, though they did not come to the same views.

A scholar in government

Unlike Yi Hwang, who preferred teaching to holding office, Yi I was an active official who believed Confucian principles should be applied directly to the running of the state. In 1568 he travelled to Ming China as a document officer with a diplomatic mission, and he helped compile the official annals of King Myeongjong. He rose to become Minister of Personnel.

He saw his era as a time of decline and argued for gyeongjang, reforming institutions so they fit present conditions. The court was splitting into rival factions, the Easterners and the Westerners. Yi I tried to calm the conflict, arguing that both sides contained good and bad men, although he came to be seen as a leader of the Westerners himself. King Seonjo did not commit to his proposals, and Yi I left office in 1583. He died the following year.

Principle and material force

Neo-Confucian philosophers asked how li (principle, the pattern of things) relates to gi (material force or energy). Yi Hwang held that the two could each initiate activity. Yi I disagreed: he argued that principle and material force cannot be separated, and that only material force moves, with principle "riding" on it. In general, his thinking gave more weight to concrete things and outer experience than to inner spiritual perception.

He also debated these questions for years, by letter and in person, with his friend Seong Hon.

Books that shaped Korean education

Yi I wrote for kings and for beginners. The Essentials of the Studies of the Sages (Seonghak Jibyo), compiled in 1581, summarised Neo-Confucian ethics, self-cultivation and statecraft. Gyeongmong Yogyeol, written in 1577 after he retired to Haeju, was a basic study guide for young learners and became widely used. His political writings include Questions and Answers at East Lake and the Memorial in Ten Thousand Words.

The 100,000 soldiers story

A famous story says Yi I foresaw a Japanese invasion and called for an army of 100,000 men. The English Wikipedia article says he warned of an attack and proposed strengthening the army, but the government rejected the idea, and he died before the Imjin War began in 1592. The Korean article notes that the specific "100,000 soldiers" claim has an unclear source and that some scholars doubt it. It is best read as a well-loved tradition rather than settled fact.

Legacy

After his death, Yi I received the posthumous title Munseong, and in 1682 he was enshrined in the national Confucian shrine. Yulgok-ro, a street in central Seoul, is named after him, and so is a Taekwon-Do pattern. Every time someone in Korea pays with a 5,000 won note, they carry a small reminder of a man who thought scholarship should make government better.

Learn with Yi I: English phrases about study and reform

Phrase	Meaning	Example
come first	get the best result	He came first in the exam nine times.
put ideas into practice	use ideas in real life	Yulgok wanted to put his ideas into practice.
self-improvement	making yourself better	He wrote about self-improvement for beginners.
see both sides	understand two opinions	He tried to see both sides of the debate.
a wake-up call	a warning that makes people act	His warning should have been a wake-up call.

Try this: Write three English sentences about a skill you want to improve, using "put into practice" in one of them and "come first" or "self-improvement" in another.