Some of my personal feelings after listening to the Clean Up seminar and some further explore.

My personal feelings:

The line is the basic element that exists in the two-dimensional space like the point and the surface. It is also the first element used at the beginning of artistic creation. It runs through the artwork and is the skeleton and the medium to convey emotions. Line elements are used in different artworks, have different expression methods, and also have their own unique particularities and limitations.