丹指丹砂,青指青雘,本是两种可作颜料的矿物,“江南金锡不为用,西蜀丹青不为采”(李斯《谏逐客书》),秦王政听信谗言,下令驱逐客卿。李斯上书说如果一定要秦国出产的东西才可以使用,那么江南的金锡不能使用,西蜀的丹青不能用于绘画。利害并举,说明了用客卿强国的重要性。丹和青可作画,泛指绘画用的颜色。“今足下还归,扬名于匈奴,功显于汉室,虽古竹帛所载,丹青所画,何以过子卿?”(班固《汉书·苏武 Dan refers to the red sand, Green refers to the Green Barley, this is two kinds of pigments can be used for the minerals, “Jiangnan Jin tin not use, Xishu Dan green mining” (Lisi “Repentance guest book”), , Ordered to deport Keqing. Li Si said that if the book must be produced in the Qin Dynasty can be used, then the southern tin can not be used, the Dan of Western Sichuan can not be used for painting. Interests simultaneously, illustrates the importance of using guest qing power. Dan and blue can paint, refers to the color used in painting. “Now enough to return, known in the Huns, Gong Xian in the Han Dynasty, although contained in ancient bamboo silk, painted by Dan Qing, why had Qing Zi?” (Bangu "Han Su Wu