Sai On was born in
Kumemura, the village within the major port city of
Naha which served as the chief center of classical Chinese learning in
Okinawa, and the source of the vast majority of the scholar-bureaucrats who were raised to serve in the administration of the kingdom. His father had likewise been a scholar-bureaucrat of Kumemura, educated in the
Confucian classics, and had served on several
tribute missions to China. Sai On's father wrote the
Chūzan Seifu by rewriting the
Chūzan Seikan in 1701. Unlike
Chūzan Seikan, which was written in Japanese
Kanbun,
Chūzan Seifu is written in
Classical Chinese. Sai On edited
Chūzan Seifu in 1724, and it is believed that this was to give the work a pro-Chinese point of view. At the age of 27, Sai On traveled to
Guangzhou in China, where he studied economics, geography, and political administration alongside the more traditional Chinese classics. Upon returning from China, Sai On was made instructor to the Crown Prince; upon the prince's accession to the throne as King Shō Kei in 1713, Sai On was elevated in position and power, and led the
investiture mission to China in 1716. In 1728, he became a member of the
Sanshikan, the Council of Three chief royal advisors. Though Sai On was not of royal blood and so could not be named
Sessei (a post which historian George Kerr translates as "prime minister"), reorganizations were undertaken within the government allowing Sai On extensive authority and powers. Under his guidance, a number of land reforms were put into place, including the reclamation of land for agriculture, relocation and establishment of settlements, irrigation, flood control, and the planting of trees. Within a few years of the beginning of the implementation of Sai On's economic reforms and construction, reclamation and conservation projects, the kingdom was producing more than ever before. dedicated to Sai On, at the
Shiseibyō Confucian temple in Naha. Okinawa's demand for wood outstripped the ability of the forests to renew themselves on their own, naturally, and the combination of
deforestation and rainy weather including regular
typhoon seasons led to extensive erosion and landslides. Sai On is particularly known for the forestry and soil conservation efforts undertaken under his guidance to combat these problems. Particular trees and sections of forest throughout the islands are still today called "Sai On pines" (蔡温松,
Sai On matsu/Sē Un machi; 蔡温並木,
Sai On namiki), and his essays on the subject of forestry and conservation remained so valued that the
post-war United States Civil Administration of the Ryukyu Islands translated, published, and distributed them abroad in 1952. In addition to these essays, Sai On produced a number of other documents, including a handbook for administrative officials in the provinces entitled
Yomui-kan, and
Ryokōnin Kokoroe (旅行人心得), or "Travelers' Advice", a guide for Okinawans abroad in China to help them in obscuring from the Chinese the relationship between Okinawa and Japan's
Satsuma Domain. A rival government faction rose up against Sai On in 1734, accusing him of being too pro-Chinese, led by a pair of scholar-bureaucrats,
Heshikiya Chōbin and
Tomoyose Anjō. Before any plots against Sai On could be executed, however, Chōbin and fourteen others were arrested and put to death. Sai On retired from his ministerial post in 1752, the year after Shō Kei's death, but remained influential until his own death at the age of 79 in 1761. ==Notes and references==