Danqing: In the poems written by the ancients, painters are often called painters. In fact, Danqing originally refers to the two mineral raw materials of temple sand and green wok. Because it is not easy to fade, it is used as a metaphor for a person's outstanding achievements. At the same time, these pigments are used when painting, so Danqing is also used to refer to the art of painting. The "painting hand" in the poem means a painter. Dan and green are two colors commonly used in ancient Chinese paintings, which refer to painting. Dan refers to red, red; Qing refers to dark green, black.