Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Yang Guangxian (1597-1669) was a Chinese Confucian writer and astronomer who was the head of the Bureau of Astronomy from 1665 to 1669. Yang Guangxian was an assistant guard commander of the Xinanwei in Anhui during the late Ming period. In 1637, he went to Beijing and then tried to advance himself by charging other people with criminal acts, or blackmailing them. When he tried this against Grand Secretary Wen Tiren, he was exiled to Liaoxi, where he stayed until the end of the Ming Dynasty in 1644. In Liaoxi, he learned astrology and fortunetelling. Upon his return to Beijing, his new skills in astrology made it possible for him to pose as an astronomer, which gave him entrance into the higher circles. But the highest positions for astronomers were all taken by Jesuits. In 1659, he wrote On Collecting Errors, a criticism of the Western calendar. He alsowrote his first attack on Christianity, On Exposing Heterodoxy.