Jiaoshi yilin 焦氏易林 "Master Jiao's forest of changes" is a book on divination with the help of hexagrams compiled by the Han-period 漢 (206 BCE-220 CE) master Jiao Yanshou 焦延壽, courtesy name Jiao Gan 焦贛 (it is not sure whether Yanshou was his courtesy name, or Gan).
He hailed from the princedom of Liang 梁 (modern Shangqiu 商丘, Henan), where he was a teacher in the household of the Prince. Later on he was appointed clerk (li 吏) in a commandery (jun 郡) and then promoted to district magistrate (ling 令) of Xiaohuang 小黃 (near modern Kaifeng 開封, Henan). His teachers were famous Confucian erudites like Meng Xi 孟喜 and Jing Fang 京房 (77-37 BCE), both of them experts in the Classic Yijing 易經 "Book of Changes". Apart from the 16-juan long Yilin, Jiao Gan also wrote the book Yilin bianzhan 易林變占, with the same length, yet this book was lost after the Tang period 唐 (618-907).
The Jiaoshi yilin explains that the 64 hexagrams of the Yijing were not only produced out of a single structure or basic hexagram (like Qian ䷀ 乾, Heaven), but could be multiplied with each other to form 4,096 new permutations. For each of these potential transformations, the author wrote a short analysis consisting of a 4-syllable rhyme, an idea that had its origin in a sentence of the history book Zuozhuan 左傳 (fenghuang yu fei, he ming qiangqiang 鳳凰于飛，和鳴鏘鏘 "The male and female phoenix fly together, singing harmoniously with gem-like sounds"; Zhuanggong 莊公 22).
The book is specialized on the explanation of the hexagrams by the changes of single lines (guabian 卦變), and the integration of cardinal directions, the Five Agents (wuxing 五行) and the Ten Celestial Stems (shi tiangan 十天干, see calendar) into the interpretation of the trigrams (najia 納甲), and the evident or hidden character of particular hexagram lines (feifu 飛伏). These changes can be seen in the continuing increase and decrease of the agents Yin and Yang 陰陽, in natural disasters or personal luck and fortune.
The Yilin is an important early writing on which many divination schools in ancient China were based, especially masters practicing divination by observing celestial phenomena (zhanhou 占候). The themes of the 64 poems for each of the 64 hexagrams deal with the wisdom and power of the ancient sage kings, the Mandate of Heaven, the importance of auspicious and inauspicious omens for the state, and Confucian virtues as filial piety (xiao 孝), humanity (ren 仁) and moral resilience (yi 義). They include quite a few folk sayings and songs and folk beliefs and such from the Huang-Lao school 黃老 which flourished during the Han period, and—most interestingly—deals in numerous places with business journeys, markets, transporting goods, and obtaining profits, for which reason Gait (2016: 11) believes that the Jiaoshi yilin was a divination manual of merchants.
|Permutation with ䷀ 乾|
|The road ascends the stony cliffs, / the Hu peoples 胡 language is just as rugged. / The interpreters seem deaf and mute, / There is not translating it. / Seeking an audience but it is not granted, / Seeking accomplishments but not acquiring merit.|
|Permutation with ䷁ 坤|
|Courting disaster and inviting trouble, / Fury descends on our country like poisonous stingers. / My arms and legs hurt, / I cannot sleep.|
|Permutation with ䷂ 屯|
|The nine in the fifth place fights for the top, / Many the regrets and delusions. / The wagon overturns, the canopy is lost, / A body used to excitement. / Accustomed to attaining desires, / Male and female follow one another.|
|Permutation with ䷃ 蒙|
|As the cuckoo and the turtledove, / Concentrate on feeding their young. / The noble is the model, / Receiving eternal joy.|
|Permutation with ䷄ 需|
|Eye twitches and leg trembles, / Joy is coming. / Young and old the family enjoys the ruler's favour.|
Translation by Gait 2016: 22. The poems are exclusively written in four-syllable verses, even if the number of verses is different. The second column gives the reconstructed original sound (to show the rhymes) according to Wang Li 王力.
Many Chinese scholars doubted that the Yilin was written by Jiao Gan. The imperial bibliography Yiwenzhi 藝文志 in the official dynastic history Hanshu 漢書, for instance, lists 13 books of experts on the Book of Changes, and 15 books on milfoil and tortoise plastron divination, but a book of Jiao Gan is not included. In the imperial bibliography Jingjizhi 經籍志 in the history book Suishu 隋書, the Jiaoshi yilin is included in the list of books on the Five Agens.
The Qing-period 清 (1644-1911) scholar Gu Yanwu 顧炎武 (1613-1682) called the Jiaoshi yilin a book of the Later Han period 後漢 (25-220 CE), while Jiao Gan lived during the late Former Han period 前漢 (206 BCE-8 CE), when the Zuozhuan was not yet made a Classic. Yet the Yilin quotes numerous sentences from the Zuozhuan, as well as sentences from the Hanshu, the history of the Former Han period that was only written in the early Later Han period.
At least parts of the text might have been written by Cui Zhuan 崔篆, a scholar living in the first decades CE, but some names mentioned in the text, like the Red Emperor (Chidi 赤帝), the Queen Mother of the West (Xiwangmu 西王母), or Wang Zhaojun 王昭君, point at a date of compilation of the early Later Han.
There is a more recent discussion on this topic, to be found in Qian Tongshu's 錢鐘書 (1910-1998) book Guanzhuipian 管錐篇.