Quyishuo 祛疑說 "Driving off doubts" is a "brush-notes"-style book (biji 筆記) written during the Song period 宋 (960-1279) by Chu Yong 儲泳 (c.1101-1165), courtesy name Wenqing 文卿, style Huagu 華谷. He hailed from Yunjiang 雲間 (modern Songjiang 松江, Jiangsu) but later lived in Huating 華亭. Not much is known about his life, except that he was an excellent composer of songs. Unfortunately his collected poems are lost except a few stanzas quoted in the Shijia dingluan 詩家鼎臠 and the Zhiyuan jiahe zhi 至元嘉禾志. His commentary on the Confucian Classic Yijing 易經 "Book of Changes", called Yishuo 易說, is quoted in Ding Yidong's 丁易東 Yixiang yi 易象義. A commentary on the Daodejing 道德經, the Laozi zhu 老子注, is also lost.
Chu Yong must have been an excellently educated person and was an expert in the three great beliefs of Confucianism, Daoism and Buddhism, and also with the art of divination (shushuYijing, and in his short book Quyishuo, in which he analyzes various kinds of prognostication as serving only the emotion by deceiving the people. In 40 short chapters, he covers all methods of divination, from oracle bones and Outer Alchemy (waidan 外丹) to burning incense, throwing money into water, exorcism, the liu-ren 六壬 method, the Five Agents, and even medical practices like pulse diagnostics and acupuncture. His book is an invaluable source about the wide range of divination or incantation practices during the Song period.
The Quyishuo is included in the series Baichuan xuehai 百川學海, Xuejin taoyuan 學津討原, Siku quanshu 四庫全書, Qingzhaotang congshu 青照堂叢書, Shuofu 說郛, Congshu jicheng chubian 叢書集成初編, and, in an abridged version with the title Quyi shuozuan 祛疑說纂, in the Baihai 稗海. A revised version with a length of 4 juan, compiled duiring the Qing period 清 (1644-1911) by Zhu Qingrong 朱清榮, is to be found in the series Yihai zhuchen 藝海珠塵.