Why Was King Sejong So Awesome?

I’m sure most of you already know about King Sejong (세종대왕) and his great accomplishments. You’ve probably stood by his statue or visited his museum in Gwanghwamun (광화문). Even if you didn’t realize it – he’s on the 10,000 won note that you use every day in Korea! Sejong’s influence isn’t just present in his statues or image but through his inventions and wisdom.

I could talk about Sejong’s accomplishments for days, but I’ll simply try and cover what has made his name ‘Sejong the Great’, and explain why he is so loved by the Korean people. Let’s get learning.

Sejong the Man

Sejong, whose real name was Yi To (이도), was born on May 7th, 1397. Sejong’s older brother, Yangnyong (양녕대군) became Crown Prince in 1404. Unfortunately, he demonstrated some erratic behavior that eventually led to his replacement by Sejong. Some people believe that his brother pretended to be mentally unstable to make his younger brother the King, but we can’t be too sure. After passing his examination, Sejong officially became King of Joseon on September 7th, 1418. This made him the fourth King of Joseon until his death in 1450.

King Sejong was awarded the title of Great after his death. This time period is a Golden Age in Korean history, full of intellectual and cultural accomplishments.

I can’t talk about Sejong’s life in chronological order or we might be all day, so let’s dive into his biggest and most significant accomplishments.


It’s not really up for debate: Sejong’s biggest and most influential achievement was creating the Korean alphabet, first known as Hunmin Jeong-um (훈민정음), ‘the correct sounds for the instruction of the people’. It was later named Hangeul (한글).

When discussing Hangeul, Sejong said: “Being of foreign origin, Chinese characters are incapable of capturing uniquely Korean meanings. Therefore, many common people have no way to express their thoughts and feelings. Out of my sympathy for their difficulties, I have created a set of 28 letters. The letters are very easy to learn, and it’s my hope that they improve the quality of life of all people.” He first announced his decision in 1443, but only planned its creation in 1446.

Although the original language had 28 letters, we’ve got it easy, because now we only use 24. A Korean syllable has three parts: an initial consonant, a peak vowel, and a final consonant. This is the same today. Sejong based the shape of each letter on the way that the sound moves outwards from one’s body. For me, it makes a lot of sense and somehow feels kind of poetic.

Unfortunately, many government officials were critical of the alphabet. The King’s officials felt that not using Chinese characters was a huge disrespect to their powerful neighbors, as well as their state ideology of Confucianism, which came from China. They even believed that it may hinder a higher level of education if they used something as simple as Hangeul. I suspect this is also because it meant that the lower classes could read and write too, putting their positions in danger.

Even though there was doubt, Sejong translated many popular poems and Buddhist scriptures into Hangeul. Not only was Hangeul a massive linguistic achievement, but a largely political one that separated Korea further from China both politically and culturally.

Even after Sejong completed the Hangeul script, people did not use it regularly for hundreds of years. Thankfully, the logistic nature of the language is now clear to linguists and Koreans alike. Some indigenous groups around the world without a writing system have even adapted Hangeul to fit their language since writing and reading it is so simple! Have you learned Hangeul yet? Don’t let the fact that it’s a foreign language scare you away – I think you can probably learn the entire alphabet in two or three days.


More than linguistics, Sejong considered himself a man of science and invention. He greatly emphasized education not only for himself but for his people.

Firstly, the arts fascinated and inspired him. He developed music by acting as a patron for orchestral compositions and court music, and even improved designs for various musical instruments.

But one of his biggest areas of achievement was science. His scientific sponsorships include many useful items that we know today such as the rain gauge, the sundial, the water clock, celestial globes, armillary spheres, and maps of the cosmos. Sejong’s bright official, Jang Yeongsil (장영실), invented most of these. Due to Jang Yeongsil’s brilliant inventions and Sejong’s great patronage, some historians and archaeologists consider Joseon to be one of the most scientifically advanced nations at the time.

The rain gauge, known as Cheugugi (측우기) in Korean, was invented in 1441. In 1434, Jang made what we would call an alarm by today’s standards! This is Jagyeongnu (자격루), which sets off a bell and drum at a specific moment through the help of water. Jang also invented the sundial or angbuilgu (앙부일구) in 1434. By playing such a large part in Joseon’s scientific renaissance, Sejong also became a better leader for it. By standardizing weights and measures and installing rain gauges across the country, he was able to rationalize his tax-assessing procedures and bring fairness to his people.

Sadly, the building where these inventions, as well as the Korean script were made, no longer stands. Jiphyeonjeon Hall (집현전) was a royal institute and library that was the cradle of academic and scientific research during Sejong’s reign. Although we can’t see the original building anymore, you can still head to Gyeongbokgung (경복궁) and feel the atmosphere – imagining what it would have been like all those years ago! It’s said that Sejong was the only King to never have missed a lecture in Confucian classics. I relate to him on a very personal level.

To encourage young scholars to study, Sejong also set up grants and scholarships from the government. He greatly rewarded those who worked hard. If a young man seemed particularly promising, he granted them a reading vacation, which was essentially paid leave for uninterrupted studying. The College of Assembled Worthies (es. 1420) helped Sejong and his pupils complete their cultural, literary, and scientific projects. His friendliness and faith in his students made him very beloved, and thankfully many of the texts from the College survive today.

Additionally, he was a commissioner of many literary works. Sejong ordered the compilation of massive historical works, and he developed branch depositories for historical records that ended up protecting the destruction of books during the Japanese invasions of 1592 to 1598. Some of the works he commissioned included a history of the Goryeo kingdom (고려시대), farming handbooks, and various Confucian texts.

Law & Civil Rights

Looking after his people was something Sejong did rather well, and something he did noticeably through law and administration. The happiness of his people was absolutely one of his number one concerns when it came to politics. In one of his famous quotes he stated; “If I have to choose two among the army, finance, and people’s mind, I will discard the army. If I have to choose one between the rest, I will discard finance. The thing that should not be discarded until the last is the people’s trust and their mind.” To achieve this, he introduced new census laws, penal reforms, and even issued some civil rights for slaves and groups outcast.

When Joseon faced issues such as floods or drought, Sejong established various relief centers to offer food, water, and shelter to his people. For farmers in particular, he reinstated a Goryeo loan system that lent out the government’s surplus grain to be paid back with nominal interest. They even invented the rain gauge invented to help Joseon’s dominant agricultural workers! Dreamy guy, I would say so?


You’re probably wondering what I can talk about next; I’ve already said so many positive things about this dude. I guess you can say I’m a bit of a Sejong fan. I briefly wanted to also introduce his achievements with the military. Since we’ve already talked about his inventions, I guess it’s no surprise that he improved various weapon systems like the military cannon. He also was responsible for initiating battles with his powerful neighbors.

To the north of Joseon, Sejong also created new territory south of the Yalu and Tumen rivers. Before Sejong, they were occupied by Jurchens, but now we can see them as part of Korea’s modern borders. In 1433, Sejong sent General Kim Jongseo to the north to destroy the Jurchen population and its settlements. He set up 10 military posts in the northern region in order to try and expand the kingdom while also keeping out Jurchen enemies.

Another key fight was when Sejong’s military invaded Tshushima Island, Japan to prevent pirating. 245 Japanese were killed and another 110 were taken captive, in comparison to 180 Korean soldiers who died. Sejong’s victory set free kidnapped Chinese and Koreans and led to the creation of the Treaty of Gyehae (계해조약) in 1443. The treaty promised that the Daimyo of Tshushima pay tribute to Sejong. In return, Joseon rewarded the Japanese with preferential rights for trading. So, it wasn’t all fun and games. But we can see that Sejong had a powerful influence over his military and a command that was sure to inspire future generations.


While Sejong was greatly admired by many, he was not always seen as perfect. In particular, Sejong had several issues that led to some officials becoming his enemy.

Firstly, Sejong had a strong connection to Buddhism, which was the state religion of the former dynasty. Confucianism was the ruling ideology of the Joseon society, and many felt uneasy with Sejong’s faith. While Sejong enforced public policies to limit the influence of Buddhism, he became even more loyal to Buddhism after the death of his Buddhist wife, Queen Soheon (소헌) in 1446.

Additionally, many historians believe that opposition to Hangeul also came from the officials growing dislike for Sejong in general. Much to their dismay, Sejong’s great love for studying and debating made him think about how his people were suffering. He believed a King with absolute power should love all of his civilians, even if they disagreed with him. This led him to be consciously fair with his interactions, particularly with his officials. It was said that he never gave any benefits to those of a higher rank simply for their position. Instead, he searched for people of great talent to work with, regardless of their social class.

Sejong was, unfortunately, not a man of great health in the later years of his life. In 1442, his eyesight began to fail, alongside his rheumatism and diabetes. He regularly asked his ministers for permission for the Crown Prince to help him run the kingdom, which was repeatedly rejected. It wasn’t until 1445, 5 years before Sejong’s death, that the Crown Prince was able to take over limited duties. As his health worsened, Sejong spent his final days writing and living in his son’s residence, where eventually died.

I hate to leave off on that sad note, but that’s pretty much the end of things. Let’s recap. Sejong the Great was the fourth king of Joseon. He was a patron of art and scientific inventions that are now used around the world. He invented the Korean alphabet, expanded Korea’s borders, and encouraged education for all of his people. Of course, difficulties came under Sejong’s reign too, and nobody is perfect. This simply gives us a deeper understanding as to why Koreans value the King so highly, and why he has his own statute in the heart of the city. What was the most interesting fact you read? Let us know in a comment below! And take our new quiz on which historical Korean figure YOU should date!

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