Gexiang xinshu 革象新書

Gexiang xinshu 革象新書, with a length of 5 juan, is a book on astronomy written during the Yuan period 元 (1279-1368) by Zhao Youqin 趙友欽, courtesy name Jingfu 敬夫, style Yuandu 緣督–the version called Yuanben gezhi xinshu–and revised during the early Ming period 明 (1368-1644) by Wang Yi 王禕 (1322–1372), courtesy name Zichong 子充, who published it with the title Chongxiu gexiang xinshu 重修革象新書.

Zhao hailed from Dezhou 德州, Jiangxi, and also wrote the books Xian-Fo yongyuan lun 仙佛同源論 (on the common origins of Daoism and Buddhism), Jindan zhengli 金丹正理 (on outer alchemy), and Mengtianlu 盟天錄. Wang Yi hailed from Yiwu 義烏, Zhejiang, and participated in the compilation of the official dynastic history of the Yuan, Yuanshi 元史. He also wrote the chronicle Dashiji xubian 大事記續編, and the essay Zhici 卮辭. His collected writings are called Wang Zhongwengong ji 王忠文公集.

Wang Yi's preface of the Chongqiu gexiang xinshu states: "[Zhao's] expertise lies in the fields of musical temperament and arithmetics (lüfa suanshu 律法算數), but he is particularly skilled in the techniques of astronomy and astrology (tianguan xingjia zhi shu 天官星家之術)." Evidence to the latter can be seen in the chapter Tuibu licheng 推步立成, which details methods of divination and verification (zhanyan 占驗). The term gexiang 革象 refers to the study of the causes behind the movements of the celestial bodies, and the changes of four seasons, with the regulations of the calendar system all included. The name of this book derives from the Daxiang 大象 commentary on the hexagram Ge ䷰革 "Revolution" in the Yijing 易經 "Book of Changes".

The book's explanations of celestial phenomena largely follow traditional methods. For instance, it states that the length of the day is due to the height of the sun's path; the coldness or warmth of the weather is due to the accumulation of qi 氣 "energy"; the zenith of the sky is far (tianding yuan 天頂遠) while the four sides are near; Yangcheng 陽城 "City of Yang" is the designation for the area below the zenith; or the belief that if shadows move to the west (ying yi pian xi 影移偏西), they are slow in the morning and fast in the evening (zao chi er wan ji 早遲而晚疾), and vice versa if shadows are inclined to the east (pian dong 偏東).

The book also holds that the heavens above the earth (di shang zhi tian 地上之天) were more than those below it (di xia zhi tian 地下之天), that the ecliptic changed its path each year (huangdao suisui bu you jiu lu 黃道歲歲不由舊路), the moon's dark spots (yuepo 月魄) were shadows of mountains and rivers, lunar eclipses were caused by the excessive reflection of sunlight (riguang duo yang ji fan kang 日光多陽極反亢), and that the sun's diameter was twice that of the moon (ri yue yuanjing xiang pei 日月圓徑相倍).

These fictitious, erroneous or superstitious statements were the reason why Wang Yi revised and abbreviated Zhao's text to a book of 2 juan length, the Chongxiu gexiang xinben. However, the places that were deleted or revised were not marked or annotated, making it difficult for readers to discern the added or removed text, and thus unable to judge Wang's merits. The revised text is concise, without the fault of being overly verbose, and has its strengths compared to Zhao's original.

Therefore, both versions were included in the imperial series Siku quanshu 四庫全書. Another edition was published in 1558 by Zhang Yuan 張淵. Wang's revised version is also included in the series Xu jinhua congshu 續金華叢書.