Yan Ruoqu 閻若璩 (1636-1704), courtesy name Baishi 百詩, style Qianqiu 潛邱, was an early Qing period 清 (1644-1911) philosopher. His family hailed from Taiyuan 太原, Shanxi, but later moved to Huai'an 淮安, Jiangsu. His biographers say that Yan Ruoqu was often sick in his youth and had to study very hard to master the traditionally venerated texts of the canon of Confucian Classics. For his motivation he sticked a placard to the door pillar, adhorting him to feel ashamed for everything he did not know, and to strive to obtain a little information from whomever he met. In the end he proved to be an excellent researcher, commentator and collator of the texs of the Classics. His hard studies had helped him to develop a stringent will to solve all inherent questions. Only in his later years he traveled to Beijing, where he attracted the attention of the Kangxi Emperor 康熙 (r. 1661-1722). After Yan's death, the emperor personally wrote the obituary text (jiwen 祭文) to his interment.
The most detailed studies of Yan Ruoqu were made to the old-text version of the Shangshu "Book of Documents", Guwen Shangshu 古文尚書. This textual tradition had been neglected in the scholarly world since the end of the Jin period 晉 (265-420). This book as well as a related text, namely Du Yu's 杜預 (222-285) commentaries on the Zuozhuan 左傳, were lost.
During the Eastern Jin period, 東晉 (317-420) the scholar Mei Ze 梅賾 submitted to the throne a text that he called Guwen Shangshu, along with a forged commentary on it, called Shangshu Kongzhi zhuan 尚書孔氏傳. The old-text Shangshu was thereupon elevated to an official textbook in the National University (taixue 太學), side by side with the new-text book Jinwen Shangshu 今文尚書. The famous Tang period 唐 (618-907) masters Lu Deming 陸德明 (c. 550-630) and Kong Yingda 孔穎達 (574-648) knew and used books from these two traditions, but only an ill-arranged 29-chapters version (a new-text version) allegedly written by Fu Sheng 伏勝 during the Han period survived. This version was believed to be a forgery, at least to the reckoning of Wu Yu 吳棫 (c. 1100-1154) and Zhu Xi 朱熹 (1130-1200), two great the Song period 宋 (960-1279) scholars. Discussions about the authenticity of Fu Sheng's version were initiated by Wu Cheng 吳澄 (1249-1333) during the Yuan period 元 (1279-1368) and Mei Zhuo 梅鷟 (c. 1483-1553) and Hao Jing 郝敬 (1558-1639) during the Ming period 明 (1368-1644), and also by the early Qing philosophers Huang Zongxi 黃宗羲 (1610-1695), Gu Yanwu 顧炎武 (1613-1682), Zhu Yizun 朱彝尊 (1629-1709), and Hu Wei 胡渭 (1633-1714). Yet none of them had carried out a systematic study of the transmitted text.
For more than twenty years, Yan Ruoqu analysed the old-text Shangshu and wrote his study Guwen Shangshu shuzheng 古文尚書疏證. He demonstrated that of the 58 chapters of the transmitted Shangshu a number of 25 had been forged during the Jin period. For his study he compared the numbers of chapters mentioned in ancient bibliographies, the names of chapters, and then the content of each chapter, paragraphs and sentences, including historiographical statements and geographical names. His findings were a scandal among contemporary scholarship because they proved that a text on which the educated elite - including the emperor - had relied on and believed in for a thousand years was a forgery.
The most important writings of Yan Ruoqu are Shangshu guwen shuzheng 尚書古文疏證, Mao Zhu Shi shuo 毛朱詩說, Mengzi shengzu nianyue kao 孟子生卒年月考, Sishu shidi 四書釋地, Shidi yulun 釋地餘論, Sangfu yizhu 喪服翼注 and Qianqiu zaji 潛邱雜記.