In 1443, King Sejong the Great, with a committee of scholars from the Jiphyeonjeon (Hall of Worthies), designed the Hunminjeongeum (훈민정음) writing system, publicly proclaimed in 1446. It is the only writing system in history with a documented author, an exact creation date, and a surviving original instruction manual (Hunminjeongeum Haerye). The 28 original letters (24 in active use today) represent the shape of the vocal apparatus when producing each sound: the consonants imitate the position of the tongue, lips, and throat; the vowels are based on ternary cosmological principles (heaven, earth, humanity). The system was explicitly designed to replace classical Chinese, which required aristocratic learning, and to make writing accessible to the entire population. The Confucian elite rejected it, calling it eonmun (언문, 'vulgar script'); its widespread use only came about from the 20th century onward. The Hunminjeongeum Haerye has been inscribed on the UNESCO Memory of the World Register since 1997.