.Why was King Sejong such an outstanding historical figure? Many assume that his personal abilities were the most important factor in his success. In fact, Sejong was quite different from other rulers. He spent the first ten years of his reign laying the foundation for monarchical rule. He founded a state research institute, the Hall of Worthies (Chiphyonjon), at the beginning of his reign, staffing it with talented officials who were encouraged to conduct a variety of research activities required for his rule. The direction of government was thus set and the quality of governance enhanced.
.Sejong believed that a king was morally obligated to ensure the common people's basic livelihood and, after that, to refine their lifestyle through Confucian enlightenment. After his tenth year in power, he sought concrete methods to promote agriculture as a means of providing adequate food and clothing for his subjects.
.Agricultural policies were at the heart of King Sejong's rule. He focused on two areas: the development of agricultural technology and the implementation of an equitable taxation system for agricultural products. On the technological front, Sejong sought to transfer the advanced agricultural techniques used in the southern provinces to other parts of Korea and to develop and distribute medical services as a means of bolstering labor efficiency.
.In the 14th century, the traditional practice of leaving land fallow was being replaced by more advanced farming techniques. By the time Sejong ascended the throne, repeated cultivation of the same crop in the same field was already common practice in the three southern provinces of Cholla, Kyongsang and Ch'ungch'ong. In 1429, on Sejong's orders, this advanced technology was studied and summarized in Straight Talk on Farming (Nongsa chiksol), an agricultural manual designed to tailor agricultural practices to conditions on the Korean peninsula. Prior to this period, Chinese agricultural techniques had been employed. Magistrates of the northern provinces were required to carry this manual with them on their new appointments and to implement its recommendations.
.At the same time, intellectuals were taking a greater interest in developments in medicine, especially pediatrics and gynecology, for the purpose of promoting population growth. This resulted in the development of an independent Korean medical science on a level equivalent to advanced Chinese medicine. King Sejong ordered the compilation and systematization of Korea's indigenous medical practices. Several comprehensive medical texts were published including the Compilation of Native Korean Prescriptions (Hyangyak chipsongbang), compiled in 1431, and the Classified Collection of Medical Prescriptions (Uibang yuch'wi). He also published a manual for the general public entitled Summary on Pregnancy and Delivery (T'aesan yorok) as part of the efforts to promote population growth. Korea's mortality rate was high, and the average couple raised only three children to adulthood in the Koryo period. After Sejong's reign, these statistics showed an upward trend.
.Korean society underwent many developmental changes after the 14th century. The Choson Dynasty played a historical role in systematically harnessing these new forces to foster a more developed state and society. As one of Choson's early rulers, Sejong performed this task conscientiously and skillfully. He believed that a monarch was obligated to feed and clothe the common people; it was "Heaven's Way" (ch'ondo). He focused on agricultural policies, repeatedly declaring that sufficient food was the "people's heaven" (minch'on). He did not limit his efforts to the promotion of agricultural technology and population growth alone. Since proper timing was essential to the implementation of advanced farming techniques, Sejong ordered local government officials to be careful not to interfere with farmers' timely performance of their duties.
.As he reflected on his responsibilities as overseer of agricultural policy, Sejong realized the Korean people did not have their own calendar. Choson was a tributary of Ming China. Each year, as the new year approached, envoys were sent to Ming to receive the new calendar. Countless problems arose from Korea's dependence on the suzerain's calendar. Koreans did not know how to reckon time frames and were thus unable to plan before the new calendar arrived. On numerous occasions officials at the Astronomy and Meteorology Bureau miscalculated days, causing considerable commotion. This was humiliating to a ruler like Sejong who emphasized timing in agricultural procedures. Thus, he decided to develop an independent system of measuring time, beginning with a survey of Kyongbokkung Palace in Seoul in an attempt to reckon days by the time determined at the palace.
.Advancements in astronomical science, one of Sejong's major achievements, along with the invention of han-gul, originated during this time. From the 14th year of his reign, Sejong mobilized scholars to invent astronomical instruments, including armillary spheres for celestial observations, and to determine the latitude of Kyongbokkung. Two years later, he ordered the development of various clocks, notably an automatically striking clepsydra (chagyongnu). Sejong later promoted further refinements in calendrical science, culminating in Yi Sun-ji's compilation of the almanac Calculation of the Motions of the Seven Celestial Determinants (Ch'iljongsan) In this work, Yi established that a lunar month lasted 29.530593 days, and a year 365,2425 days.
.Equitable Taxation System
.As another aspect of his agricultural policies, King Sejong deemed that the establishment of a fair land tax system was crucial During the Koryo Dynasty, the land tax was levied on three categories based on the fertility of the land. However, by the 14th century, this standard was no longer applicable because agricultural technology had replaced the traditional practice of leaving land fallow with repeated cultivation. New farming techniques could transform inferior plots to medium- or superior-grade land and vice versa. Reform of the land tax was thus inevitable.
.King Sejong began looking into this problem in the 12th year of his reign, and after painstaking consideration, the Tribute Tax Law (kongpop) was promulgated in 1444, the 26th year of his reign. Sejong took more than 10 years and polled 200,000 people, including many farmers, in devising this system. Where else in the world in the 15th century were farmers asked their views on land tax reform? In 1437, Sejong tilled his own plot of land in Kyongbokkung. He applied the directions printed in his agricultural texts in a courtyard where many of the astronomical instruments he had helped create were located, testing to see if his recommendations to farmers were in fact effective.
.According to the Tribute Tax Law, land was divided into five categories, while the harvest in a certain year was graded into nine classifications. The shift from three to five land categories reflected a better understanding of new circumstances that had resulted from technological innovations. Estimates of harvests had been made in the past in the areas inflicted by natural calamities, but this was the first time these estimations were incorporated into a general system. The reform process took such a long time because it was difficult to develop a reliable yield evaluation. An unexpected solution came about in 1441 with the crown prince's invention of a rain gauge.
.Choson kings often suffered on account of droughts. King T'aejong, King Sejong's father, was a prime example. He blamed his own moral deficiency for the droughts that plagued his reign, and after 18 years he relinquished the throne to his son Sejong. While dry spells had been frequent during this period, new agricultural methods had aggravated the problem. Wet rice agriculture was becoming popular and more fields were being moved from the foothills to wider plains. Irrigation became a factor because rainfall was the only source of water for these open fields.
.King Sejong directed every village to measure how much rain was absorbed in the soil and to report this information to the court along with records of rainfall The crown prince (later King Munjong) invented a rain gauge while measuring rainfall at the palace. It had occurred to him that instead of digging into the earth to check rain absorption, it would be easier and more accurate to use a standardized container. The invention of the rain gauge, two centuries before an Italian inventor introduced such a device in Europe, was a by-product of King Sejong's interest in farming.
.The rain gauge was immediately adopted as a tool in the evaluation of annual yield for the land tax system. The instrument was created in the fourth month of 1441, and by 1442 King Sejong had installed one in every district Rainfall data were reported to the Ministry of Taxation through local magistrates. In 1441, the Tribute Tax Law was finalized and promulgated A year later the evaluation system was judged to be objective and accurate in each district
.King Sejong's agricultural policies came to a grand conclusion in 1445, with the promulgation of the Royal Message on the Encouragement of Agriculture (Kwonnong kyoso) In this pronouncements Sejong asked for the cooperation of government officials and farmers. He reiterated his request that officials refrain from forcing farmers to provide corvee labor service and asked the farmers to carefully observe the agricultural calendar. From test results following recommended agricultural methods, the king found that the average farming household in Kyonggi-do province could produce "several times" more (He did not offer specific numbers.) and introduced a law limiting corvee service to 10 days a year for farmers.
.Sejong's achievements derived from his grasp of the historical tasks before him and his sincere commitment to his subjects. As his policies for the improvement of living standards began to show results, he gradually introduced other policies aimed at popular enlightenment He sought to use music as a way to promote Confucian harmony among the people and created the Korean alphabet to provide the common people with a more accessible writing system. King Sejong was committed to the Confucian government ideal: After the necessities of life-food, clothing and housing-had been satisfied, people should focus on leading ethical, humane lives.
.With this in mind, Sejong looked for a medium through which his subjects could be taught the ethics and morals of Confucianism. Early on, during his 14th year in power, Sejong ordered the scholars at the Hall of Worthies to compile outstanding examples from Korean and Chinese history concerning the "Three Fundamental Principles in Human Relationships" (filial piety, loyalty to the state and wifely devotion). The results were printed in a book entitled Conduct of the Three Fundamental Principles in Human Relationships (Samgang haengshildo). However, it was recorded in Chinese characters, making it incomprehensible to the general public.
.The new Korean alphabet was invented in part to make such Confucian texts accessible to the common people. When objections to the alphabet were raised in 1446, King Sejong refuted such criticism by ordering the translation of Conduct of the Three Fundamental Principles in Human Relationships into han-gu!. However, this translation was not completed until the reign of King Songjong some 30 years later.
.The creation of han-gul was an important result of King Sejong's practical humanitarianism. By its promulgation, he sought to make it easier for the common people to learn. He has been remembered as a "sage king" because he contributed to the improvement of living conditions for the common pe0ple and to the development of Korean culture within the Confucian political framework, which regarded the people as "the foundation of the state."