Huang Gongwang put forward "the method of mountains and rivers, care about the contingency". Dong Qichang once wrote, "painting... In which straight chapping is used, and this method is also used for a long time." That is to say, the "straightness" discussed in painting is not only the reservation of existing skills at the time of painting, but also the meaning of straightness, that is, to be "flexible" and frank, that is, to use the pen when painting works, only in this way can we draw the landscape in the painter's mind, so that it can be displayed in the picture.