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Sejong the Great was born in 1397 as Yi Do, the son of Taejong, the King of Korea. Taejong already had two older sons, and – since the Confucian ideals which dominated Joseon society stressed respect for elders, and therefore primogeniture – both preceded the young Yi in the line of succession. However, Sejong’s eldest brother, the scandalous Yangnyeong, proved himself to be a philanderer and truant. Taejong accordingly deemed him unworthy and stripped him of his imperial titles, disinheriting him. Sejong’s other older brother, Hroryeong, elected to become a monk, and in doing so renounced his princedom, clearing the way for his younger brother. Thus, although Sejong was not born to be a king, he soon found himself heir apparent.

Compared to his brothers, he was a model crown prince; although physically weak and sickly, he was utterly devoted to his studies, to the extent that his father banned him from reading books. In order to make way for a smooth succession, King Taejong formally stepped down in 1418, and the twenty-year-old Sejong ascended the throne. However, the old monarch maintained a vice-like grip on power, and officials seen as obstacles in Sejong’s rise were ruthlessly removed from court. Taejong finally passed away in 1422, and Sejong at last became monarch in more than name.

He quickly proved himself a gifted administrator, promoted the spread of Confucianism and reorganised the internal structure of the Korean imperial court. Sejong was very socially minded, especially by the standards of the Joseon Era, setting aside grain reserves for peasants in case of famine and even establishing a form of maternity leave for serf women. He created an academy for twenty scholars, named the Hall of Worthies, and encouraged his court scholars to study astronomy, history and medicine, despite tradition dictating the duty of academics was to thoroughly study Confucian ideals. 

Sejong’s intellectual interests also included novel technologies and inventions. He sponsored the creation of a metal movable-type printing press, two-hundred years before Gutenberg produced a similar device – although Sejong’s press had limited effectiveness due to the fact most of the Korean populace was illiterate. Other inventions sponsored by Sejong include the first rain gauge, sundials and clocks. Many of these breakthroughs were made by Jang Yeong-sil, a close friend of Sejong.

Jang was born a peasant, but his scientific brilliance was such that Sejong was adamant that he work at the palace. This was a radical departure from the norm, since Joseon Korea operated under the strictest of social hierarchies, which forbade even the hint of social mobility. Unfortunately, Jang eventually built Sejong a gama (a throne-cum-carriage carried by servants), but this contraption collapsed while Sejong was sitting in it. Jang’s jealous enemies, seizing the opportunity, used this incident as an excuse to oust him from power, jailing him and expelling him from the palace.  

The King’s greatest contribution to the arts and sciences, however, was the creation of the Korean alphabet. For centuries, Korea had used a pictographic script, which heavily resembled Chinese. The language was extremely difficult to learn and inconvenient, since a scribe had to learn thousands for characters for different words. Sejong decided it would be far simpler to use an alphabetic featural script (in which characters represented letters instead of words) and personally devised the new alphabet himself.

This alphabet eventually became known as Hangul, and consists of blocks, each of which contains a single syllable and has a place for a starting consonant, vowel and ending consonant. Each individual letter was designed to be easy to write, and reflects the shape the mouth, tongue and lips make while forming a sound. For example, the consonant that sounds like a hard ‘g’ is written as ‘ㄱ’, reflecting how the tongue is raised when making that sound. 

Hangul faced a strong backlash from the conservative classes, the yangban, who claimed that this new alphabet was less refined than the Chinese character system. It is worth remembering, however, that these aristocrats had a vested interest in keeping peasants and women illiterate, and so their complaints should be regarded with some suspicion. Despite their criticism, the script was readily adopted, since it was clear that it was logical and straightforward. A common saying of the time was that a genius could learn Hangul in a matter of hours, while a fool could master it in ten days. Today, the use of Chinese characters has all but faded away, and Hangul is the official alphabet of the Korean language. 

Though Sejong’s reputation is built on scholarship and invention, his reign also witnessed substantial military accomplishments. Only one year into his reign, Sejong sent an expedition to quash the wako, Japanese pirates operating on the island of Tsushima. By the end of 1419, the wako had been crushed, securing safe passage for Korean ships and seafarers. Twenty years later, the ruler of Tsushima would pledge fealty to the King as part of the Treaty of Gyehae. 

Yet Sejong was not able to enjoy his successes. He was plagued by political turmoil and the machinations of his court had greatly restricted his power. He was forced first to restrict and then to persecute the practice of Buddhism, which had grown into a powerful force – despite Sejong being a believer himself. Throughout his life, Sejong suffered from deteriorating health, including rheumatism and blindness, and died an early death aged 53, upon which he was given his formal regnal name – Sejong daewang: Sejong the Great. Soon after he passed away, the country collapsed into chaos, since his son Munjong died a mere two years later. Sejong’s second son, Sejo, eventually usurped the throne and abolished the Hall of Worthies, ending the glory of Sejong’s prized institution of scholars.

Thanks to his achievements, Sejong has been engrained into the national fabric of South Korea. Today, he appears on the 10,000 won bill, and his statue peers over Gwanghwamun Plaza in central Seoul. During his reign, Sejong had made countless scientific advancements, expanded his Kingdom’s reach and worked tirelessly to improve the lives of his subjects; he was an enlightened despot before his time. 

Kim-Renaud, Y., 1997. King Sejong the Great: The Light of Fifteenth Century Korea. International Circle of Korean Linguistics