Dongtian qinglu 洞天清錄 "Pure records of the Cave Heaven", also called Dongtian qinglu ji 洞天清錄集, is a book on antiques written during the Song period 宋 (960-1279) by Zhao Xihu 趙希鵠 (1170-1242), a distant relative of the imperial house.
The short book explains how to collect and appreciates antiques like zithers, inkstones, bells and ritual bronze vessels, strangely shaped stones, inkstone screens (yanping 硯屏), brush recks (bige 筆格), small water pots used for calligraphy (shuidi 水滴), autographs (hanmo zhenji 翰墨真跡), rubbings of stone inscriptions, colour prints and coloured paper (zhihua yinse 紙花印色) and paintings. Zhao Xihu's book is very helpful not only for the history of collecting antiques, but also concerning a lot of cultural objects whose use he explains, like diaodou 刁斗 (a kind of cooking utensil used during travels and military campaigns), bronze figures of real or fabulous animals that were used as oil lamps (and not as water dispensers, as often believed in his time).
Zhu Quan 朱權 (1378-1448), Prince Xian of Ning 寧獻王 of the Ming dynasty 明 (1368-1644), loved this book so much that he patronized its first print and marketization. The compilers of the imperial series Siku quanshu 四庫全書 called this book a "compass for the connoisseur" (shangjianjia zhi zhinan 賞鑒家之指南). The Dongtian qinglu is included in the series Gezhi congshu 格致叢書, Tang-Song congshu 唐宋叢書, Xinang guangyao 奚囊廣要, Shuofu 說郛, Siku quanshu, Duhuazhai congshu 讀畫齋叢書, Haishanxianguan congshu 海山仙館叢書, Congshu jicheng chubian 叢書集成初編 and Meishu congshu 美術叢書.
|古琴以斷紋為證。琴不歴五百歲不斷。愈久則斷愈多。然斷有數等。||Ancient zither can be recognized by crack patterns. There are no cracks in zithers younger than 500 years. The older they are, the more cracks are visible. Still, there are different classifications of numbers of cracks.|
|有蛇腹斷。有紋橫截琴面，相去或一寸或二寸，節節相似如蛇腹下紋。||Snake belly cracks stretch along the face of the instrument, in a distance of 1 to 2 inches, and much similar to the segments on the belly of a snake.|
|有細紋斷。如髪千百條，亦停勻，多在琴之兩旁，而近岳處則無之。有面與底皆斷者。||Fine crack patterns like hundreds of fine hair, also evenly distributed, on both sides of the zither, but not close to the bridge. Some have cracks on the upper side and the bottom.|
|又有梅花斷。其紋如梅花頭，此為極古，非千餘載不能有也。||There are also plum blossom cracks that resemble the heads of plum blossoms. They are extremely old and can only be found on instruments that are older than one thousand years.|
|蓋漆器無斷紋而琴獨有之者，蓋他器用布漆，琴則不用。他器安閒，而琴日夜為絃所激，又歲久桐腐而漆相離破。斷紋隱處雖腐，磨礪至再重加光漆，其紋愈見，然真斷紋如劍鋒，偽則否。||That lacquerware has no cracks, while zithers have them is because other ware is covered with a lacquer coating, and zithers not. Moreover, other objects rest quietly, while the strings of zithers are plucked day by day. Finally, the wooden material of the zither rots over the years which tears the lacquer coating apart. Even if the part of the cracks is rotten, it is possible to sand and polish it and add a new layer of lacquer. Still, then, the cracks are visible, like the edge of a sword. This is how genuine cracks can be told apart from fake ones.|