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Sejong the Great

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Sejong the Great was the fourth monarch of the Koreanic state of Joseon.

10000 won serieVI obverse
10000 won serieVI obverse

He ruled from 1418 until his death in 1450. Sejong is widely regarded as the greatest king in Korean history. He is most famous for creating Hangul, the native alphabet of the Korean language. His reign was a period of massive growth in science, technology, medicine, and the arts. He also focused on making life better for common people through various reforms.

Sejong was born Yi To in 1397 in Hanyang, which is modern-day Seoul.

He was the third son of King Taejong. Because he was a younger son, it was not expected that he would become king. However, Yi To was very gifted and studious. He loved reading so much that stories say his father once took his books away for his health. He was skilled in calligraphy, painting, and the gayageum, a traditional string instrument. These academic interests prepared him for leadership.

His path to the throne involved a major change in the royal family.

Front view of the Imperial Throne Hall Geunjeongjeon at Gyeongbokgung Palace with blue sky in Seoul
Front view of the Imperial Throne Hall Geunjeongjeon at Gyeongbokgung Palace with blue sky in Seoul

His older brother, Grand Prince Yangnyŏng, was the original crown prince. However, Yangnyŏng had many behavioral issues and often disobeyed the king. In 1418, King Taejong decided to remove Yangnyŏng from his position. The king chose Yi To to be the new successor because of his wisdom. In mid-1418, Yi To became the crown prince. A few months later, Taejong stepped down, and Sejong was crowned king at the Geunjeongjeon hall in Gyeongbokgung Palace.

To drive progress, Sejong reestablished a research organization called the Hall of Worthies in 1420.

Sujeongjeon
Sujeongjeon

This group acted like a modern think tank for the government. It provided education for the king and the crown prince. The Hall of Worthies also oversaw many important intellectual projects. In 1426, Sejong introduced a system called jejak. This allowed scholars to conduct independent research without doing daily government work. This was similar to how modern research grants work today.

Under Sejong, Joseon saw a "golden age" of scientific discovery.

BoRuGak Jagyeongnu
BoRuGak Jagyeongnu

After a solar eclipse in 1432 was predicted incorrectly, Sejong pushed for better astronomical tools. Scientists created an armillary sphere in 1433 to study the stars. In 1434, a man named Chang Yŏngsil designed a water clock. This device helped the city track time accurately. In 1441, scientists also invented the ch'ŭgugi, which is a rain gauge. This tool measured rainfall and was used widely across the country. These inventions helped the state manage agriculture and time more effectively.

Sejong also focused on practical knowledge for the people. The Hall of Worthies produced a massive 365-volume medical text called the uibang yuchwi.

They also created the Nongsa chiksŏl, which was a book about farming.

農事直說 농사직설
農事直說 농사직설

This text helped farmers improve their production. Sejong also introduced tax and land reforms. These changes helped increase food production and lowered tax rates for many people. He even expanded the northern borders of Korea by managing groups known as the Jurchens.

Despite his many successes, Sejong faced personal challenges. He suffered from recurring and worsening health issues throughout much of his life. By 1445, his health required him to let the crown prince handle daily government affairs. He also dealt with religious tensions in his court. While he promoted Confucianism, he was privately a Buddhist. This caused disagreements with the Confucian officials in his government. He died in 1450 at the age of 52 and was buried at the Yeongneung tomb.

Today, Sejong remains a powerful icon of Korean culture.

Hunminjeongum
Hunminjeongum

His name is used for Sejong City, and his face appears on the 10,000 won banknote. He is remembered as a leader who used science and literacy to empower his people. His creation of a native writing system changed the course of Korean history forever. His legacy is one of intellectual growth and social improvement.

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🖼️ Images & Media (16)
File:Front view of the Imperial Throne Hall Geunjeongjeon at Gyeongbokgung Palace with blue sky in Seoul.jpg
Front view of the Imperial Throne Hall...
File:Sujeongjeon.JPG
Sujeongjeon.JPG
File:BoRuGak Jagyeongnu.JPG
BoRuGak Jagyeongnu.JPG
File:의방유취 (醫方類聚).jpg
의방유취 (醫方類聚).jpg
File:갑인자 (3).JPG
갑인자 (3).JPG
File:農事直說 농사직설.jpg
農事直說 농사직설.jpg
File:Korean rocket arrows.jpg
Korean rocket arrows.jpg
File:Encykorea-악장가사 여민락.jpg
Encykorea-악장가사 여민락.jpg
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Dream Journey to the Peach Blossom Land.jpg
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朝鮮通寳 - Dr. Luke Roberts.jpg
File:삼강행실도 (1).jpg
삼강행실도 (1).jpg
File:PB9C-15C 001 三綱行實圖 삼강행실도 109 (cropped).jpg
PB9C-15C 001 三綱行實圖 삼강행실도 109 (cropped).jpg

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