Qiankun tiyi 乾坤體義

Qiankun tiyi 乾坤體義 is a theoretical book on astronomy written in Chinese by the Italian Jesuit missionary Matteo Ricci (Ch. Li Madou 利瑪竇; 1552–1610). He arrived in China in 1582 and was first active in the region of Guangdong, but went to Beijing in 1601, where he presented to the court of the Ming dynasty 明 (1368-1644), among others, a mechanical clock and a world map, and so caught attraction. Together with the Chinese converts Xu Guangqi 徐光啟 (1562–1633), Li Zhizao 李之藻 (1571–1630) and Zhou Ziyu 周子愚 he transmitted Western knowledge of mathematics and astronomy to China. Ricci mastered Chinese quite well, but for his translations, he relied on the support of Chinese colleagues. His most important books are Tianwen shiyi 天文實義 on astronomy as well as Tongwen suanzhi 同文算指 and Jihe yuanben 幾何原本 on mathematics.

His Qiankun tiyi has a length of 2 juan. The first part discusses celestial phaenomena, while the second fascicle deals with arithmetic, the science of the earth (mainly geometry and geodesy). Ricci divided the earth's surface into five climatic zones (han-wen wudai 寒溫五帶) and the sky with the seven celestial bodies (qizheng 七政; sun, moon, and the five visible planets) and the fixed stars (hengxing 恆星) into nine layers (jiu chong 九重). He also introduced the Aristotelian concept of the classical elements water, fire, earth, and air, into China (si da kangxing 四大亢行). The book explains eclipses (boshi 薄蝕) on the base of the movements of the sun, the moon, and the shadow of the earth (diying 地影) and holds that the rising and setting of celestial bodies generates "atmospheric obstruction" (mengqi 蒙氣).

The book was first printed by Yu Yongning 余永寧. It is included in the imperial series Siku quanshu 四庫全書.