attach great importance to his Christian conversion and identity. Works Military science Xu Guangqi wrote a book on military techniques and strategies entitled Mr Xu's Amateur Observations in response to the criticisms he faced for daring discuss military matters in spite of being a mere scholar. He frequently cited the Xunzi and Guanzi, and made use of rewards and punishments along the lines of the Legalists, at least in relief activities. Xu Guangqi put forward the concept of a "Rich Country and Strong Army" (富國強兵), which would be adopted by Japan for its modernization in the end of the 19th century, under the name Fukoku Kyohei. Mathematics In 1607, Xu and Ricci translated the first parts of Euclid's Elements (a treatise on mathematics, geometry, and logic) into Chinese. Some Chinese scholars credit Xu as having "started China's enlightenment". Astronomy After followers of Xu and Ricci publicly predicted a solar eclipse in 1629, Xu was appointed by the Emperor as the leader of an effort to reform the Chinese calendar. The reform, which constituted the first major collaboration between scientists from Europe and from the Far East, was completed after his death and became known as the Chongzhen calendar. It's notable for systematically introducing the concepts and development of European mathematics and astronomy to China for the first time, including extensive translations and references to Euclid's Elements and the works of Nicolaus Copernicus, Johannes Kepler, Galileo Galilei, and Tycho Brahe, whose Tychonic system was used its main theoretical basis. Agriculture Xu Guangqi wrote the Complete Treatise on Agriculture, an outstanding agricultural treatise that followed in the tradition of those such as Wang Zhen (wrote the Wang Zhen Nong Shu of 1313 AD) and Jia Sixia (wrote the Chi Min Yao Shu of 535 AD). Like Wang Zhen, Xu lived in troubled times, and was devoted as a patriot to aiding the rural farmers of China. His main interests were in irrigation, fertilizers, famine relief, economic crops, and empirical observation with early notions of chemistry. It was an enormous written work, some 700,000 written Chinese characters, making it 7 times as large as the work of both Jia Sixia and Wang Zhen. Although its final draft was unfinished by Xu Guangqi by the time of his death in 1633, the famous Jiangnan scholar Chen Zilong assembled a group of scholars to edit the draft, publishing it in 1639. The topics covered by